Cock-ups can also generate conspiracies.  In the light of the information de Gondi provided about the nuclear scaremongering activities of Litvinenko and Scaramella in Italy, it seems likely that the presence of polonium in London was linked in some way to these.  The most notable use of polonium is as a 'trigger' in relatively primitive nuclear devices.

To have light cast on such murky goings-on would have left many in London with egg on their faces, so it is highly likely that CYA became the order of the day. As a result we ended up with a torrent of preposterous disinformation, designed to pretend that an accident was murder -- one conspiracy to cover up another.

Some very diverse -- and interesting -- people have been exploring disinformation networks, among other matters, on both sides of the Atlantic.  In the UK, much interesting information has appeared on site called Spinwatcha site called Spinwatch, which is linked to a kind of Wiki called Spinprofiles.