Boris Johnson quizzed on Europe stance
12 December 2012 Last updated at 20:18 GMT
Boris Johnson has said investors in Britain "would welcome clarity" about the country's European Union future and that it is time a referendum was held.
The UK should reshape its membership, opting out of some elements, including the common agricultural and fisheries policies and social chapter, he said.
He was confident David Cameron could deliver such a deal, which could then be voted on, Mr Johnson told Jeremy Paxman.
The prime minister is to make a major speech on Europe within weeks.
Watch the Newsnight discussion on how Britain would fare outside Europe, with senior business, political, European and cultural guests on Wednesday 12 December 2012 at 22:30 GMT on BBC Two. Or catch up afterwards on BBC iPlayer.