The Last North British Type 1 Diesel


In 1958, the North British Loco Co in Glasgow delivered the first of the company’s last Type 1 diesel electric loco for British Railways, which was also one of the very last orders for the company, before its demise just four years later. Order L78 was the third of a group of four placed by BTC on 16th November 1955, and was for the ten Bo‑Bo Type 1 freight locomotives.

North British had made an unsuccessful transition into designing and building the new form of traction, not helped by British Railways decision to commit to electric rather than hydraulic transmissions. NBL had teamed up with Voith of West Germany, and built hydraulic transmissions for the BR designed diesel-hydraulic locomotives based on the German V200 designs.

But, it must be noted that the first truly British Railways main line diesel locomotives were the North British Built “Warship” class, Nos. D600 to D604 with hydraulic transmissions and put to work on the Western Region.

The company’s first work in Britain for the main line railways actually came from the LMS in 1947, with the design and building of No. 10800, and finally delivered in 1950. This was ordered for branch and secondary line work by the LMS, and outshopped from NBL’s Queens Park Works to works order L977, with an 827hp Paxman engine, British Thomson Houston traction motors, and perhaps the forerunner of all BR designs for this type of work until the 1980s. It did have some intriguing means of operation, with the main engine turning the main generator through a chain drive, and the BTH control and electrical systems were electro-pneumatic – later common to all AEI designs.

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BR’s first Type ‘A’ / Type 1 Bo-Bo diesel was built by North British Locomotive Co. in Glasgow. The similarity with the later design is obvious in this view.

Mitchell Library copyright notice

This first Bo-Bo Type 1 design was sold to Brush Traction after 1959, and used as a test bed under the Brush “Hawk” project, before finally being scrapped in 1976.

However, from both North British and BR perspectives, its legacy lay in the Glasgow company’s final main line diesel orders, and the BR Modernisation Programme gave the company the opportunity to compete for work in the ‘new technology’ era. Under the programme, the railway industry was required to produce examples of various types of diesel and electric locomotive, for pilot scheme trials and evaluation in a range of options, designated by type-letters “A”, “B” or
”C”, covering various power ranges and operational needs.

The company already had agreements with diesel engine builders, hydraulic, and electric transmission suppliers, and had built BR’s first mixed traffic diesel locomotive, with electric transmission.

NBL Type A Diagram

Three of the original British Railways Type “A” weight diagrams, which ultimately became Type 1 from 1957/58

For North British this was the third of a group of four placed by BTC on 16th November 1955, and became Order No. L78 for 10 Bo‑Bo Type ‘A’, (later designated Type 1) freight locomotives. The agreed delivery schedule was 21 months from the date of settlement of technical details, which would have been August 1957.


As it turned out these NBL Type 1’s did not appear until the late summer of 1958, a year behind schedule, which in itself given the lack of experience of main line diesel traction on Britain’s railways, and operating conditions was not such a surprise.


D8406 built by nbl copy

As new from NBL’s Queens Park Works, carrying BR No. D8406 – this would carry works number 27677, to order L78

Mitchell Library copyright noticeWhen they finally arrived, in overall appearance they were similar to the solitary 827hp locomotive, delivered to BR in 1950 as No. 10800.

Principal Dimensions

D8400 - dimensions

Their construction was based on fabricated mainframes, running the full length of the locomotive – almost clearly following steam locomotive practice. This in layout in turn supported a single Paxman 16‑cylinder 16YHXL engine, and was carried on a pair of four‑wheeled bogies, with a single driving cab.

The engine itself was Paxman’s preferred vee form, and at 1250 rpm, it developed 800bhp, driving the GEC main and auxiliary generators, with the same arrangement adopted in the D6100 series design from North British.

Electrically, the six‑pole, self‑ventilated main generator, was running at 1250 rpm, and developing 550kW, 1700 Amps, designated type WT881. The traction motors were identical with the D6100 series, but were downrated to 152hp, running at 420 rpm, with the electro‑pneumatic control system, as in the D6100 series.


The class were all built at the Queens Park works, formerly the works of Dubs & Co., but amalgamated with the other two main Glasgow companies in 1903 that formed the North British company. During the 1950s, the company found it very difficult to translate their steam era engineering skills to meet the modern diesel and electric needs. That said, the company’s successful arrangements with Voith and MAN saw the Queens Park Works manufacturing hydraulic transmission systems and engines in the 1960s, although few of these were used on BR.

d8409-stratford-slide-Grahame Wareham

The last of the class at Stratford in 1969 shortly before being scrapped, in BR plain green livery, with half-height yellow warning panels, and of course, the NBL diamond works plate has been removed. This is definitely one of those diamonds that did not last forever!
Photo: © Grahame Wareham

In service, with British Railways Eastern Region, they carried running numbers D8400‑D8409, but were not equipped with train heating boilers. They were allocated at first to the Devons Road depot in London – which was BR’s first depot to be converted to diesel only operations, and then moved to Stratford where they spent the remainder of their working lives.

Although allocated numbers and a classification of ‘16’ under the TOPS scheme, but they were never carried.

The Paxman engines fitted to the class reportedly suffered from frequent engine seizures that were put down to inadequate ventilation, along with similar reports of other engine problems. It was also noted that the type used electro-mechanical control, where increasing numbers of BR locos from other builders were fitted with an electro-pneumatic system.

They spent all of their working life at Stratford depot, in North London, and once again, like their NBL built contemporaries, suffered an early withdrawal under the criteria of the 1967 National Traction Plan. They barely reached a 10-year lifespan – though much of that was out of use, and they were withdrawn between February and September 1968, and by the end of 1969 all of the class had been scrapped.