If you look at Britain's export designs, then there were several contenders for supplying diesel locomotives in the early post-war era.Multiprinter wrote:Perhaps the only certainty is that English Electric would have supplied diesels to both companies and quite possibly of the same 'off the peg' design.
Metropolitan Vickers supplied Crossley-engined locos to Australia and Ireland (not very good ones)
BRCW supplied Sulzer-powered locos for Australia and Sierra Leone (though I think the touting for sales was actually done by the London sales office of Sulzer Bros)
EE were supplying locos to several markets
North British supplied a few locos with MAN engines to the Indian sub-continent and one to the LMS (again not very remarkable)
The most likely is probably EE, as the LNER had worked with Armstrong Whitworth between the wars and must have known the staff - most of whom went to EE after AW gave up building locos in the mid-1930s. Some of these staff had earlier worked for Beardmore.
I believe there was some anti-Swiss and anti-German sentiment in the immediate post-war period too, so NB and BRCW might have had problems.
US builders might be an outsider - Alco built locos for Portugal, Spain and Greece, for example, and Baldwin for France. Britain was being urged to export to survive though, so domestic products seem the only politically correct option.
If EE-powered locos were built they could have been designed by the LNER, just like the Bulleid locos on the Southern. My query is what justification there was for them though. The LNER built a lot of Pacifics in the post-war era and probably had a surplus of very new or newly-rebuilt locos. Once the coal crisis eased there was less and less incentive to use oil and more to use coal from the newly-nationalised pits.