The Twenty-Two

In 1955 diesel locomotives were a rarity on Britain’s railway network. Although there were quite a lot of diesel shunters, many of English Electric manufacture and due to become the standard type throughout BR, the number of mainline locomotives could be counted on the fingers of two hands! Despite this lack of practical experience and with brand new steam locomotives being built to modern standard designs, the British Transport Commission had ordered 14 different mainline diesel types straight off the drawing board for in-service evaluation. The manufacturers included English Electric, Metropolitan-Vickers, Brush, BRCW, Beyer-Peacock and North British along with BR’s own workshops. Whilst all had experience in building steam locomotives, only English Electric had more than limited experience with diesels. The diesels ordered in these initial batches varied from 800HP to 2300HP and roughly mirrored the various steam equivalents at each of the ‘Types 1-4’.

English Electric was a conglomerate of companies drawn together in the aftermath of World War I to pool their manufacturing knowledge. Among these was Dick Kerr – a locomotive manufacturer. During the 2nd World War, Napier’s were added to the English Electric group as the company became involved in aviation. In the mid 1950’s the Vulcan Foundry and Robert Stephenson & Hawthorns became part of the group bringing a huge amount of railway locomotive manufacturing experience and capability. Thus EE acquired the ability to become one of the key manufacturers of BR’s diesel fleet in the rush to replace steam and modernise the railway. That breadth of knowledge and experience resulted in the production of probably the most successful of the modernisation classes.

English Electric were not shy of the ‘Private Venture’ – building something that a government department didn’t yet know it wanted! They also could come up with innovative solutions to government specifications. In aviation the Canberra (so good the US Martin company built hundreds under license as the B57 for the USAF) and the Lightning stand out as exceptional types. But it is on the rails that EE demonstrated its ability to produce something different that the customer hadn’t even realised they needed.

In the 1950’s Britain’s railways were facing the competition from the private car and airlines for the first time. One answer sought by the British Transport Commission was electrification and the West Coast mainline was chosen to carry that particular torch. But in other operating departments finding ways to stave off the competition with new diesels no more powerful than their steam counterparts was concentrating the mind. The key factor to make the railway competitive was speed over intermediate distances – 75 to 300 miles. On shorter distances the car is king whilst air travel only really becomes viable over 300 miles – as long as the train is fast enough. The calculations done at the time (and ironically just as valid in the UK today) indicated that an average speed for the journey of 75mph was needed to be commercially viable. For the East Coast mainline from King’s Cross to Edinburgh, this was especially key to remaining a competitive route.

In October 1955, whilst already working on a range of diesels that the BTC knew it wanted, English Electric unveiled a prototype locomotive called Deltic. It offered 3,300Hp and 105mph capability at a stroke and was the most powerful single unit diesel locomotive available anywhere in the world. In terms of the locomotive superstructure and running gear, it was quite standard – the wheel arrangement was Co-Co (3 axles to each bogie, each individually powered by a traction motor). The body was of all welded steel construction. The loco weighed in at 106 tons – light compared with the type 4’s already in construction that would tip the scales at close on 140 tons! How had EE done it?

The Deltic took its name from its diesel engines. When English Electric took charge of Napier in 1942 they gained access to specialist engine technology which had originated in the birthplace of the diesel – Germany. In the late 1920’s Junkers Motorenwerke were looking to make a reliable diesel engine for aeroplanes. The outcome of their work was the Jumo two-stroke engine. It worked using horizontally opposed pistons to form the combustion chamber. Napier’s approached Junkers to buy the knowledge soon after and by 1934 had created their own aero engine. During the subsequent war the technology was used for the Napier Sabre petrol engine in the Typhoon fighter – by now produced in an H-configuration. Meanwhile, the Royal Navy required high powered and light weight diesel engines for their motor-torpedo boats. Again Napier’s had the answer – a triangular engine using the same horizontally opposed piston technology. This ‘Deltic’ engine would give the admiralty 2500HP with 1000 hours life between overhaul. It was these engines, built for a life on the waves that EE looked to for their new locomotive. In railway terms, 1000 hours between services is not acceptable but EE derated the engines to 1650HP which increased the hours to 6000 and made the locomotive viable.

Deltic underwent extensive trials but probably most of those were the wrong trials – shifting 18 coach loads over Shap for example. It was the operations team on the East Coast who realised the true potential – 3300HP with a 10 coach train meant that the magical 75mph average speed was really attainable. The business case was put to the BTC for 23 Deltic locomotives to replace 55 pacific steam locomotives (with the associated reductions in crews, maintenance personnel and ancillary items). It was probably a no-brainer, especially as EE had offered a maintenance contract which involved swapping out of engines with maintenance carried out at the factory and reliability clauses (very ahead of the time). Even so the BTC felt the need to indicate that it was still boss and reduced the order to 22.

The prototype Deltic retired after 400,000 miles of running and spent many years in the Science Museum before being relocated to the National Railway Museum. The production Deltics entered service in 1961/62 and, with a number of modifications over the prototype, began to fulfil their potential and gave the East Coast a real boost in improved schedules. The anticipated 6000hr period between overhauls took more than 5 years to achieve and the shortfall was paid for by the manufacturers under the service agreement. In service the 22 Deltics achieved 150,000-200,000 miles per annum. They oversaw incremental improvements in journey times on the East Coast mainline – changes to track alignment combined with their prodigious acceleration making King’s Cross to Edinburgh possible in 5 ½ hours with stops. In steam days it was 7 hours 20 minutes non-stop.

As a type the Deltics commanded a huge following amongst enthusiasts. Being the most powerful express passenger locomotives on the railway certainly helped and experiencing the acceleration from 80mph when every other type had ‘run out of steam’ was something else! That they were named also played its part. The locomotives based in the north at Haymarket and Gateshead were named after army regiments – fittingly, my favourite was D9016 Gordon Highlander. The Finsbury Park locomotives took the LNER tradition of being named after famous racehorses. The advent of the High Speed Trains on the East Coast saw the Deltics relegated to semi-fast duties from 1978 onwards. They were gradually phased out of service between 1980 and 1981 with the last three being retained to run farewell services in January 1982. The crowds of enthusiasts on King’s Cross station to see off the last Deltic hauled train made the national news.

Sitting in my office around 2.5 miles from New Southgate station on a warm, humid, summer evening I find myself recalling that in the 1970’s I could hear Deltics on their way north from Kings Cross as they passed Alexandra Palace and then, following the short time in Wood Green Tunnels, onwards through Southgate and on to New Barnet and beyond. I can occasionally hear HST’s but it’s not quite the same… Such is progress I guess!

The details in this post are a flavour of the history and of what was achieved. There will rightly be some rail enthusiasts reading this who would prefer a degree more detail – I crave their indulgence as I am writing to a wider audience. For those of my readers who would like to gain a fuller appreciation I would recommend the book ‘The Deltics – A Symposium’ though it is currently out of print, so you may need to order it through the library.


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