So the BBC was blegging last night for information on Transaero's B737 EI-DDK, an aircraft involved in the Litvinenko case which is reportedly all hot with po-210. You just knew this blog would end up being involved, didn't you?
Transaero is a fairly respectable outfit, set up as a competitor to Aeroflot in 1991 and mostly operating Boeing types from Moscow-Domededovo. EI-DDK is a 737-4S3, serial number 24165, which has been knocking around unremarkably since 1989. Transaero bought it off Boeing's resale division in 2003.
It was in Heathrow on the 28th-29th of October, having come from Moscow, which is presumably why it fell under suspicion - reportedly, Lugovoi, Kotvin and Co. travelled aboard it on their way to meet Litvinenko. Arriving on the 28th; leaving on the 29th. The last photo I can find of it puts it in Tegel Airport, Berlin on the 2nd of December.