During 1963 a delegation from Cuban National Railways (Ferrocarriles Nacionales de Cuba) visited Britain and held discussions with British Railways on the feasibility of converting modern British designed and built locomotives for use in Cuba. In 1964, as a result of the information received on that visit, Cuban National Railways placed an order with Brush for 10 locomotives based on the design of the new Type 4 Sulzer-engined diesel-electric machines that they were then building for British Railways.

Whilst welcome, the order was sensitive and shrouded in secrecy. Hawker-Siddeley, Brush's parent company, had valuable interests in the defence industry - particularily in the USA. Due to the volatile political situation between the USA and Cuba following Fidel Castro's Communist revolution, the Cuban missile crisis, plus the ill-fated Bay of Pigs incident earlier in the decade; followed by US trade sanctions being imposed against Castro's Cuba, Hawker-Siddeley recognized that it would not be prudent to have this new trade connection generally known in the public domain, for fear of endangering their US interests.

In order to avoid any embarrassment to Hawker-Siddeley (and their many subsidiaries) an elaborate subterfuge was devised. To the press in particular, and the rest of the world in general, it was announced that the Cuban loco's were constructed by the Clayton Equipment Company at their Hatton works near Derby - a company with no connection whatsoever to Hawker-Siddeley. The ten machines were even fitted with Clayton builder plates on the cabsides - it is not known if internal components were similarily 're-badged'. Clayton were responsible for the less than successful Class 17 machines built for British Railways as a part of the 1957 Dieselisation Programme and were, by 1964/5, in the absence of further orders from BR, in financial difficulty and unlikely to suffer unduly by upsetting American defence chiefs.

To put the record straight: the bodyshells and most of the components for the Cuban locomotives were manufactured at the Falcon Works, although it appears that works numbers were not assigned. Some of the heavy assembly work was also done by Brush but final assembly and painting was performed by International Combustion Ltd., a company based in Derby. The semi-complete machines were moved there on makeshift bogies adapted from wooden bodied wagons. The 10 completed locomotives were tested on the Derby-Bristol line, usually under cover of darkness, and always light-engine as the buck-eye coupler prevented the connection of coaching stock. 2501 & 2502 were shipped to Cuba from Hull docks on July 30th 1965 aboard the Yugoslav freighter 'Kolasin'; an event which, despite all of the secrecy, was reported on the front page of the Hull Daily Mail! 2503 and 2504 followed on September 2nd, 2505 on October 18th, and 2506 on October 26th. Precise dates for 2507-2510 are not known but all 10 locomotives were in Cuba by early 1966. In order to provide facilities for assembly at the Falcon Works it was decided that the construction of D1842 to D1861 (Brush numbers 604-623) should be undertaken elsewhere; originally this was to have been the Beyer-Peacock Works at Gorton in Manchester, but was changed to BR's works at Crewe.

Although sometimes referred to as the Cuban '47s' this is, technically, inaccurate. The power unit used in the Cuban order machines was the French-built Sulzer 2,534hp 12LVA24 engine rated at 1,050rpm that was installed in five of the BR production build machines - D1702 to D1706; which were later designated as Class 48 under TOPS. The engine was supported by Brush electrical equipment modified to cope with the anti-clockwise motion of the twin bank 'V' formation engine. The Brush designation for the loco's was the 'T' Class, which became the T975 Class in Cuba.

The only other significant technical difference between the Cuban machines and the production Class 48's was the provision of additional cooling equipment to handle the tropical heat and humidity of Cuba, this is visually apparent by the modified roof grilles fitted above the main cooling group.

The exported loco's were numbered 2501 to 2510 and equipped with air-brakes only, no train heating capabilities (not really required in Cuba and, in any case, the machines were intended for freight use only), no front headcode panel (obviously!), a full width 'cow-catcher' lower front (not fitted until arrival in Cuba) with a red drawbar and buck-eye coupler, illuminated number panels on each corner, and a large circular headlight fitted on each cab roof flanked by air-horns. The class-standard two-tone green paint scheme applied to the British loco's was used, although the roofs were painted white rather than green. A small yellow warning panel was applied to the front (this was probably to satisfy BR's regulations during test runs, rather than at the behest of the Cubans), standard BR transfer serif-style numbers were also applied to the bodysides but, again this was probably to satisfy BR requirements during testing.

After arrival in Cuba the loco's retained, initially at least, the original two-tone green livery; although a thin yellow stripe was later added to the top and bottom the central Sherwood green band, and "Ferrocarriles de Cuba" (Railroads of Cuba) lettering, also in yellow, was added to the upper bodyside. The class designation 'T975' was assigned and all 10 were renumbered (in sequence) from T975 to T984, but were later, oddly, renumbered back to their original numbers with a "5" added to the front (2501 and 2503 might not have carried these numbers). All were eventually repainted in a red livery with a white stripe along the upper bodyside, and a double white chevron on the front wrapping round to the cabside.

Beyond the cosmetic changes noted above very little is known about these Cuban Brush Sulzers and their work on Castro's isle. Spare parts were probably a problem and only one spare LVA unit, two spare bogies, and a few other bits were supplied. A Clayton engineer was on-hand during the early days, but later there would have been little locally available Sulzer expertise.

To hypothesize for a moment... In 1971 Hawker-Siddeley sold the experimental HS4000 Kestrel to the Soviet Union - where there must have been some expertise to keep the machine with it's 4,000hp Sulzer 16LVA24 engine running. It has been suggested in some quarters that Soviet engineers visited Cuba to inspect the Brush machines and subsequenlty incorporated certain aspects in their own designs. It is a known fact that the Cuban National Railway imported Soviet-built locomotives from the 60's onwards, ergo It is not too far-fetched to suppose Soviet engineers with Sulzer experience could have been involved in the maintenance of the Brush-built machines using, possibly, 'cloned' parts made in the USSR.

What is known is that all of the machines were withdrawn from service by February 1992 and dumped at Cardenas where several were known to be extant in 1997, and possibly as late as 2000. Photographs show a large square hole cut into the bodyside at the number one end, close to the main cooling group, that was certainly not there originally; this may have been done to salvage small parts. It appears that all ten machines have now been cut-up.

Whatever the situation was regarding parts and maintenance, it is evident that some of the loco's, at least, remained in operational service for almost 27 years; a creditable acheivement - this term being more than 20 years longer than that of the BR Class 48's (which were all rebuilt as Class 47's by the early 1970's), and as long as many, and longer than some, of their BR Class 47 brethren!