In WW2 the US and UK agreed to pool production resources - production being allocated in such a way that overall production was maximised. The UK was relatively good at building fighters and heavy bombers; a lot of UK production was focussed around that. US military production grew as a stupendous rate during the war; in part due to the US government telling industry what they wanted and letting industry figure out the best way to do it. A lot of the existing US armament industry was rapidly embarrassed by civilian industry producing things like machine guns several times faster and at a much reduced cost.
Check out 'Freedom's Forge' by Arthur Herman - the US production statistics are truly jaw dropping.
During the war, the UK imported the bulk of its advanced trainers (Harvard) and transport aircraft (Dakota) from the US. As such, it didn't really have a civilian airliner industry at the end of hostilities. The US on the other hand had the Dakota (which was essentially a military version of a successful airliner) and the C54 Skymaster - a four engined transport, again with civilian roots. The Lancastrian was an attempt to convert an excellent airframe - the Lancaster - to civilian use as a short term way of competing.
The Lincoln was only ever intended for military use - it was a further development of the Lancaster airframe and engines. Indeed, it's original designation was Lancaster Mk IV.