It may be a bleak mid-winter for the world economy but the US and UK leaders insist a thaw will come.President Barack Obama and Prime Minister Gordon Brown say the various measures they have taken — bail-outs, stimulus packages and long-term budget plans — will have the desired effect. But neither has given a timeline for recovery. Brown, who will address Congress later, said they agreed on the need for greater financial regulation on a global scale. “We’ve just been talking about the need for proper supervision of shadow banking systems, of areas where there was bank practices that were unacceptable, where remuneration policies got out of hand and weren’t based on long-term success, but on short-term deals,” he said. This week has seen further dramatic falls in world markets, particulalarly Wall Street. Both leaders have stressed that getting banks lending again and restoring confidence in financial markets are key to recovery.