ahh but didn't the B-29 enter late in the war and as a result went unpainted, and i know for certain the RAF DID use B-29's under the codename 'Washington'.
B-29s were named Boeing Washington B.1 in RAF Service. Eighty-seven B-29s served on loan with RAF Bomber Command from 1950 as a longer-range nuclear-capable bomber pending the introduction of the English Electric Canberra in quantity.
Most Washingtons had been returned by 1955 although two or three remained in the UK as gunnery targets.
In fact not all the aircraft were B-29 bombers, three aircraft were RB-29s, the dedicated reconnaissance/ELINT version. These aircraft were part 192 Sqn at RAF Watton.
The ELINT Washington’s flew sorties around Baltic, Black and Caspian Seas, monitoring Russian signal transmissions. Occasional sorties were also mounted along Russia’s Northern border with Norway.
None of the ELINT Washington’s were ever shot down, but they were intercepted by Russian fighter aircraft a number of times, mainly over the Black Sea area.