Your concern is misplaced: You have reversed the arrow of cause and effect. I claimed that it might be possible to infer something about the power of the UK from the course of events surrounding the Litvinyenko affair, not that the affair signalled the end of the UK's power! The latter is of course ridiculous, and it is most interesting that you made this mistake.

I understand very well what it means to be British, being from Britian, living there as well as having lived in other countries and being very au fait with contemporary psychological theories on social identity.