Trackside Classic: 1961 British Rail Class 55 ‘Deltic’ Diesel Locomotive – A Distinctive Roar of Confidence on Britain’s Rails

very smokey deltic

(first posted 12/5/2014)     CC has already heard the story of Mallard, the world’s fastest steam locomotive and pride of the London and North Eastern Railway. But by 1960, Mallard and her sisters were around 25 years old, and ‘old tech’ – expensive to run, fuel and maintain, with a high demand for hard, unpleasant and dirty labour. Steam was increasingly out of date in the new jet age.

Their successor was just as distinctive. When new, it was the most powerful single unit diesel locomotive in the world, and it is still one of the most distinctive and charismatic ones ever. Thanking loyal CC follower Big Paws for the detail research and picture selection, let’s take a look at the Deltic.

prototype train

By the late 1950s, Britain was a more confident and fast changing country. Wartime damage had largely been repaired, and post war austerity was a fading memory (wartime food rationing finally ended in 1954) as economic growth and consumerism took hold. The National Health Service and improved state education were, with things like television, affordable motoring and foreign holidays, improving the living standards of many ordinary people.

Improved main trunk roads and bypasses were beginning to join up to create a new modern network, and the first motorway opened in 1959. With more disposable income came more cars (the number of cars in the UK doubled from 1948 to 1958) including such milestones as the Morris Minor, the Mini, the Jaguar E-Type and, later, the Ford Cortina and Morris 1100 (BMC ADO16).

Prototype on test

National engineering ambition and confidence was evident not just in the Mini but also the de Havilland Comet, the world’s first jet airliner; the English Electric Lightning, Britain’s first supersonic jet fighter; and the Avro Vulcan, the great delta winged nuclear bomber, and in nuclear power. And, by 1960, Concorde and the Queen Elizabeth 2 ocean liner were on the drawing board. Britain was also preparing for a largely peaceful and democratic transition from Empire to Commonwealth.

But it was a different story for the railway system, British Railways (BR). Rail had been nationalised in 1947 as part of the great post war transformation of Britain under the hugely influential Labour government of Prime Minister Clement Attlee, with four regional companies with strong and very different traditions and identities being forced together.

But nationalisation had not been accompanied by investment, and it showed, with steam power still dominant outside the London commuter network. In 1955, an ambitious Rail Modernisation Plan was launched, with promises of new investment in diesel locomotives and electrification of key routes, but delivery was slow and the results disappointing.

prototype 01

A range of prototype locomotives was built by the locomotive industry in the hope of fleet orders. Most turned out to be underpowered or unreliable, or both, and crucially there was a lack of central direction and standardisation that looks, in hindsight, nothing short of shocking. Despite nationalisation, BR was still largely operating as four semi-autonomous Regions, based geographically on the predecessor companies. Rivalry between the Regions was as intense as anything between, say, Austin and Morris within BMC.


The Western Region (the old Great Western Railway) chose diesel hydraulics derived from German practice. The London Midland Region, linking London, Birmingham, Manchester and Glasgow, opted to electrify like the French. The Southern Region, working across southern England, expanded its pre-war third rail electric system. And the Eastern Region – the old London and North Eastern of Flying Scotsman and Mallard, on the 400 mile key East Coast Main Line (ECML) linking London with Yorkshire, north east England and onto Edinburgh – chose an English solution to the challenge of replacing the most famous and beautiful steam engines in the world.


The Eastern Region was lucky enough to be led by Gerard Francis Gisborne Twisleton-Wykeham-Fiennes (known as Gerry Fiennes), who saw the weaknesses of the early diesels and the threat of the car and the new motorways more clearly than others. Fiennes was determined that his expresses would move into the diesel age with a step change in performance to match the new competition and rejected the Modernisation Scheme prototypes as just not fast or powerful enough, and looked elsewhere. His chosen solution came from a perhaps unlikely source.

Deltic advert

English Electric was an engineering conglomerate better known for power station equipment and jet aircraft (the Canberra and the Lightning) than railway locomotives, but they had an ace up their sleeve. One subsidiary was D. Napier and Son, who had a similar history to Rolls-Royce of expensive cars, and specialist marine and aero-engines.

Jumo 204

Napier had a licence to build the German Junkers Jumo 204 engine. This was an opposed piston two stroke diesel engine, originally intended for aircraft use.  Being of opposed piston configuration, a separate crankshaft was needed for each piston bank, with some pretty complex gearing to bring it all together. Effectively, the two opposed pistons created a combustion chamber between them, the combustion in which then powered both pistons.


However, it was compact and flat (or tall and narrow), and had no heavy cylinder head and being a two stroke, no valves either. Seen here, it is installed in the Junkers F24.

By 1945, Napier focussed on marine applications and used the Junkers Jumo as the basis of a marine engine for the British Admiralty. Napier developed a version for use in motor torpedo boats, with three opposed cylinders (and therefore six opposed pistons) in a triangular formation, driving three crankshafts. The concept was easily expanded, with nine and 18 cylinder versions being developed, with three or six engines lined up on the three crankshafts. Through the 1950s and beyond, the Royal Navy used Deltic engines in several classes of minesweeper and torpedo boats, with great success. The secret was the high speed of the engine – up to 1500 rpm, more than twice that of traditionally configured engines.

prototype 02

The compact size and light weight – less than half that of comparable conventional diesels – of the Deltic engine, coupled with its high power capacity, were big attractions for rail use. In 1955, English Electric linked two 18 cylinder Deltic engine, each rated at 1230kw, or 1650hp, with mechanically driven blowers (or supercharger) and charge coolers (intercoolers), powering an EE generator, to create a prototype 3300hp express diesel locomotive, known simply as Deltic. It looked like no other British diesel, in a striking pale blue livery with cream lining and broad chevrons on the nose.

Unlike American diesels, the layout was symmetrical, with driving cabs at both ends, a practice that is almost universal in Europe. The defining feature was the size – 70 feet long, and 13 feet high –the maximum that could be accommodated on Britain’s rails, riding on twin three axle bogies (trucks), with all axles powered by electric motors – a wheel arrangement known as Co-Co in Europe.

Deltic engine in situ

But despite the great size and massive power, weight was just 106 tons – compared to the 133 tons of EE’s other express offering, the 2000hp Class 40 which had no more power than a steam Pacific. And, against the 2000hp of the Class 40, Deltic offered 3,300hp from its two 18 cylinder engines – with a massive boost in acceleration and the ability to sustain high speed.

obligatory train set box

Of course, as you’d expect, the publicity people and modelmakers went into overdrive. Hornby Dublo (or Double-O gauge – get it?) model trains were the leading British model train brand of the 1950s and 1960s, and this is a pretty fair visualisation of many a train platform of the time. This was an engine schoolboys would gather on the platform to see.

CC 171 105 1200

In comparison, the EMD E series was rated at just 2400hp. Even today, with half a century’s advance in diesel engine technology and in electronics to control the power delivery, the standard mainline American diesel – such as the General Electric ES44 series – max out at 4400hp. At the time, and until the problematic EMD SD45 of 1966, the Deltic was the most powerful single unit diesel locomotive in the world. In 1955, Deltic was something spectacular, and just what Fiennes was searching for to power his modern expresses.

prototype and production

EE had big ambitions for the Deltic – the striking colour scheme and large headlight on the prototype were intended to demonstrate its suitability for export to North America and the British Commonwealth. These ambitions were never realised, and were probably not even remotely realistic in 1955, given the complexity of the design. But Gerry Fiennes and the Eastern Region liked it, and ordered a fleet of 22 to dieselise the ECML, which were the only production versions built. These replaced a total of 55 Pacific steam locos.


The production Deltics had toned down styling and a sober but attractive two tone green livery, but were mechanically little changed from the prototype. They were built at the EE-owned Vulcan Foundry in Newton le Willows, Lancashire, a producer of steam engines for the British Empire that EE had acquired in 1957 (and a plant that could trace its history back to Robert Stephenson, son of George), and entered main line service in 1961-1962.

east coast express

In line with the British tradition for express locomotives, the Deltics were given names, carried on each side in bold aluminium nameplates (which are now very collectible and very valuable). Eight Deltics based in London were named after famous racehorses; the six based in Gateshead (across the River Tyne from Newcastle upon Tyne, the regional capital) and the eight based in Edinburgh were named after British Army regiments from Yorkshire and north east England and from Scotland respectively – units such as the Green Howards, Durham Light Infantry, Royal Northumberland Fusiliers, Royal Scots Grey, Black Watch and Argyll and Sutherland Highlander that are now all obsolete as regiments have merged and dissolved over half a century, but which many still remember.

Picture of Class 55 Deltic locomotive number 55022 Royal Scots Grey at Newcastle central station. At 3300 horsepower, the BR Type 5 Deltics were one of the most powerful diesel locomotives ever used in front line service in the UK.

From 1966, onwards, the smart green livery was replaced by the new BR standard ‘rail blue’, to match blue and grey coaches, and with the famous ‘double arrow’ symbol replacing the lion and wheel of the steam age. It had taken 20 years since nationalisation, but now, for the first time, all of Britain’s railways looked the same – and different, as blue was deliberately chosen as a colour with few historic railway associations. The famous InterCity brand was also introduced at the same time, with the Deltics as the flagship. The all-over blue served to emphasise further the sheer bulk of the Deltic, giving it even greater presence and sense of power.


The ECML and the Deltics were an almost perfect match. The first 250 miles north from London are among the flattest, straightest and fastest mainlines in Britain, and the Deltics could exploit their ability to accelerate a heavy train to 100mph and cruise at that speed for many miles. With the Deltics in service, Fiennes could launch a massive acceleration; in 1962 the standard London– Edinburgh time came down from seven hours to under six – beating the pre-war Coronation streamliner, which was a one-off service, not a six times a day standard fare express.


But the effect was not a one-off; progressive improvements in the quality of the track, and major projects to improve the alignment through stations and curves, allowed for the timetable to be steadily tightened over the years. By 1975, without increasing the maximum speed, another half an hour had been cut from the London – Edinburgh time. Deltics routinely exceeded their stated 100 mph maximum – most observers agree that the occasional 115 mph may well have been achieved

So what makes the Deltic special? The looks and the colours of the prototype; the sheer bulk of the production versions. The impact of these huge engines pulling expresses at a steady 100mph for mile after mile. The rarity – only 22, compared to 200 Class 40s and over 500 Brush Class 47 diesels. But most of all, the noise. Ah, the noise. Compare the noise of any other British diesel to a Deltic and you’ll get it. It’s like comparing a bus to a racing car. The former is slow, steady and chugs along.

smokey deltic

But the Deltic spins frantically, emitting huge clouds of black smoke as the engine starts up (a recurring problem caused by oil build up in the exhausts, and source of more than one fire) and settles in a fast, frantic idle; then, the second engine starts (this beast is twin engined, remember), and it all happens again. In the cavernous stations at King’s Cross, York, Newcastle Central and Edinburgh Waverley, an idling Deltic drowned any PA system, and a departing one would seemingly be audible for minutes.

royal scots grey

Shutting down the engine was no less dramatic, as the complex gearing around six crankshafts rattled to a stop. Growing up just 100 yards from the ECML, two miles from Wakefield station on the London – Leeds line, we always knew when a train was Deltic hauled minutes before it passed between the houses across the road, and the noise had a direct line of sight to our house.

2 Deltics KX

The Deltics needed specialist maintenance, because of the complexity of the unique engine design, with dedicated maintenance teams, pushing up their running costs. This was the weakness of Fiennes’ plan – reliance on a small, complex and expensive fleet for the key services. BR standardisation was truly in full flow by the mid-1970s, and the Deltics (and the Western Region diesel hydraulics) were identified as non-standard and expensive, and there was no talk of the any of the BR Regions going alone.


From 1976, the HST Inter City 125 (or High Speed Train – two diesel electric power cars sandwiching 8 or 9 new Mark 3 coaches) began to supplant the Deltics on the East Coast, with another big acceleration to exploit their 125mph capability on existing infrastructure – London- Edinburgh came down to 4 ½ hours. The HST was the fastest diesel train in the world. (Another CC is due, to mark it’s 40 years of frontline express service. And still the fastest diesel train in the world.) But, without Fiennes’ vision and determination, it is conceivable that BR would have limped through the 1960s with expresses struggling to improve on steam times, with no long distance express business for the HSTs to take over.

king edward bridge gateshead

So the Deltics were relegated to second tier duties – semi-fast trains between London and York were a favourite – and to other routes. But a Deltic on a cross country train that ran on the slow lines and never got over 70mph was a sad sight – like a thoroughbred limping round a muddy field.

at blea moor

Six of the 22 production Deltics are now preserved (by far the highest percentage for a British locomotive class) plus the prototype, which went to the Science Museum in London as soon as Fiennes had ordered his fleet. Seven out of 23 rivals the eight out of 25 Union Pacific Big Boys. Four Deltics are active in the mainline charter and excursion market, and King’s Own Yorkshire Light Infantry has a key slot in Britain’s National Railway Museum.

But the Deltics’ real home was at the head of a fast express and, at their peak, in the mid-1970s, thundering across the Vale of York at 100mph on the Flying Scotsman, accelerating a heavy train through the tunnels outside London King’s Cross, crossing the great bridges over the Tyne at Newcastle or across the great viaducts of northern England, there was nothing to touch them for power and presence in passenger train service in the world.

There still isn’t.


Related reading: Union Pacific EMD E9: The Last of the Classic Diesel Streamliners