kr79:
Could it be this 3vgt project was dropped as the t45 range was origanly envisiged to be launched around 1975 so rather than devolp a new cab for say 5 years production seemed less atractive than devoloping existing parts to come up with the marathon.As for Germans been better engineers i wouldnt say thats true. But to say the allies win tge war as the brits were better engineers is ridiculous.
Just like the ERGO the T45 was already obsolete even by the standards of when it was introduced at least in terms of it’s cab design and it’s in house TL12 engine before the change to outsourced options.
As for British engineers as good as,if not better,at the very least. 
So you’re saying that the WW2 could have been won ‘if’ we hadn’t introduced the idea of steam turbines in our war ships years before and hadn’t managed to get ahead in radar technology and were still relying on reciprocating engines to go up against ships like the Bismark and to hunt down U Boats in the battle of the Atlantic and ‘if’ we didn’t have aircraft like the Spitfire to maintain air superiority during the Battle of Britain and in Europe after D Day considering the abilities of the Me 109 and then FW 190 D9 being superior to just about every other allied aircraft type.
As for tanks the British Comet ( would have been ) a much better bet to face anything which the Germans had,for anyone unlucky enough to have to served in that type of warfare, than anything which the Americans turned out.That issue only not causing the defeat of the allied forces after D Day because the Germans ran out of 88 mm amour piercing ammunition before the allies ran out of unfortunate Sherman tank crews.( Just like in the case of Leyland years later it’s development being delayed by the cash issue just as the Rolls Merlin would have been if Rolls hadn’t been lucky enough to beg for the private investment to develop it ).Or if we hadn’t had the Griffon Spit to keep the Me 109’s and FW 190’s away from the lame old Hawker Typhoons who’s lack of performance was again a reflection of the lack of development cash compared to the later Tempest and Fury.