Although the 25 British Conservative Party MEPs have left the European People's Party to form the European Conservatives and Reformists Group (ECR), the EPP remains the strongest bloc in parliament with 264 seats.

BBC: Euro parliament elects new leader

But, in a move seen as an attempt to appeal to the right, he has pledged to pull his party out of the European People's Party in Brussels.

BBC: David Cameron

Even before he was prime minister he pulled the Conservative Party out of the European People's Party grouping in the EU, incurring the displeasure of German Chancellor Angela Merkel, the EPP's leading light, and thereby excluding himself from the most powerful caucus that shapes decisions ahead of European summits.

WSJ: Cameron's Plans Bring Fears, Schadenfreude