old iron wrote:
In terms of truly historic arcraft, the Science Museum in South Kensington is one of the best in the world (just behind NASM and the Musee de l'Air, in that or reverse order). A small collection, but kg for kg perhaps the very best. Not much in the way of WWII planes, but the ONLY Fokker Eindecker, an Antoinette, other early birds (Cody, Roe), the Vickers Vimy (first to Australia), Gloster (oldest surviving jet in the world), the Supermarine Schnieder trophy wnner, the WWII aircraft (Spitfire, Hurricane) generally have combat histories, and other things. And you can get far closer than you can to aircraft in most other major musuems - I have a photo of myself between the floats of the Schneider racer.
The Science Museum is the English Smithsonian. And if you can talk your way in - I did, so it is possible - the back rooms in Wroughton, about 100 km west of London, have not a lot of aircraft but everyhing else that you can imagine: hundreds and hundreds of very early cars, buses, trains, bikes, tractors etc. all stored in the original hangers of an old RAF base.
The Imperial War Museum has some things as well, but much of that can be seen elsewhere; what the Science Museum frequently has is what can be seen nowhere else.
This is good advice.
I will add a plug for the British Museum. Possibly the best museum in the world (no airplane stuff, though). Imagine if you were the preeminent world power during the 16th-19th centuries when there weren't as many reservations about going to an archeological site and taking what you wanted. Well, the Brits were, they did, and eventually many of those items ended up in the British Museum.