Mr Sikorski is close to a number of senior Conservatives and was a member of Oxford University’s Bullingdon Club at the same time as Boris Johnson, the Mayor of London. The recordings, leaked to Polish magazine Wprost, purportedly capture a conversation between Mr Sikorski and Jacek Rostowski, a former finance minister. Mr Sikorski is reported to have said of Mr Cameron’s attempt to renegotiate the UK’s relationship with Brussels: “It’s either a very badly thought through move, or, not for the first time, a kind of incompetence in European affairs.