If you drill down carefully - particularly in the RAF - you'd be amazed how much of what was sent wasn't used, or wasn't liked.it has been my experience in talking to Americans and Europeans that we do tend to over state the importance of lend lease.
Some of this was down to it being a "way" of getting some use out of fast-becoming-obsolete equipment...Lockheed Hudson as a day bomber anyone? Bell Airacobra? P40 versus Me109 in the Battle of Britain??? C-class four-stacker destroyers?
Its REAL use in a lot of locations was releasing other equipment for more "front line" use - intelligent planning put slower ships in convioys that the fourstackers could protect, releasing the new corvettes and faster RN destroyers for better defence of "priority" convoys. As 1940 went into 1941, lend-lease equiped squadrons in RAF Groups north of the Thames allowed Fighter Command to group its more-combative aircraft for "Circuses" over France. Hudsons, Venturas etc, allowed Bomber Command to recoup some Whitleys and Wellingtons from maritime patrolling with Coastal Command for the first massed raids.
Certainly there are tales of Ex-Soviet nuclear boomers sitting rusting beside concrete piers in Archangel and Murmansk...and as the old period concrete crumbles away, the rusty tangles of old Allied materiel that was just bulldozed in as "fill" is starting to show thru!
BUT
The GREATEST contribution of Lend-Lease in Western Europe - Britain, France, the US versus Germany - was actually in the INFRASTRUCTURE set up to support the aircraft. Lend-lease saw the huge Boeing european repair depot effort starting in 1940 with the establishment of Station 359 Langford Lodge in Northern Ireland, which received every Boeing aircraft - and a whole range of others who subcontracted from Boeing - later to fly into Western Europe, for final fitting and maintenance before unit allocation, and repair in the event of major combat damage. The Fortresses, Liberators, P-38 Lightnings etc of the USAAF in Europe were repaired there and fast....the whole establishment having set up - breaching ALL neutrality regulations! - to support/maintain Lend-Lease aircraft from when they began to arrive in the UK. The "RAF" Catalina that found the Bismark didn't actually fly from Castle Archdale on that recce mission as always said! LOL It was an RAF - BADGED aircraft being used to give AMERICAN crews experience of wartime operations! But on those few days it was "all hands to the tiller"...in other words, as the USAAF began its huge daylight bombing offensive of targets in Germany by four-engine'd heavies, and tragets in france by Mediums - there were thousands of Boeing or Boeing-trained fitters and mechanics ready at Langford Lodge and throughout the UK READY to service and support the assault!
There used to be a very small but excellent museum on part of the old Langford Lodge site given over to Station 359, but it closed a few years ago. Langford Lodge (the runway bit! LOL)is STILL a satellite field for Belfast International Airport, and the home of the Ulster Aviation Society and their museum. And also on the site is a world-wide construction company called Mivan - who have the contracts for the modular-construction KFC and McDonald's restaurants that they assemble around the world!!!
Lend-Lease has gone full circle!
....of course there are some who say that THAT is about as useful as it was originally! brrrrrrrrrrrrrrrrrpP!