* FTSE 100 up 0.5 percent * Yellen says Fed needs to do more to aid economy * Burberry gains as sales rise above $1 pounds * Centrica falls after warning on earnings By Alistair Smout LONDON, Nov 14 (Reuters) - Britain's top shares rebounded on Thursday, led higher by energy stocks after the Federal Reserve's Janet Yellen eased worries the U.S. central bank may start scaling back its stimulus programme this year. Yellen, in remarks released ahead of the Senate hearing on Thursday to confirm her as new Fed chair, said the central bank had "more work to do" to help the economy. That suggests she is in no hurry to start trimming the bond-buying programme that has fuelled an equity rally this year. Having trimmed gains throughout the session, the index received another leg up as her confirmation hearing began. "There's some hope that Yellen will prove to be the second coming of (current Fed chief) Bernanke, and that means a continuation of the easy money, long equity trade that has worked so well in recent months," IG sales trader Will Hedden said. "Based on what's she said, it seems they won't do anything especially soon." With appetite for risk boosted by Yellen's comments, cyclical stocks such as oil and gas companies rallied, adding a 8.5 points to the index's gains. The FTSE 100 rose 29.04 points, or 0.5 percent, at 6,659.04 by 1536 GMT. It had fallen sharply on Wednesday after the Bank of England gave a stronger forecast for the UK economy, bringing forward expectations of when interest rates will rise and sending sterling higher, hitting exporters. British luxury brand Burberry was up 1.8 percent after first-half sales exceeded 1 billion pounds ($1.6 billion) for the first time. "The results are another welcome indication of the healthy position (CEO) Angela Ahrendts leaves the firm in when she passes the reins onto Christopher Bailey next year," Toby Morris, senior sales trader at CMC Markets, said in a note. However, earnings remain a concern for investors in Europe. Equities have re-rated above long term averages, even though profits and revenues continue to disappoint. Fifty percent of firms in Europe have missed analysts' earnings forecasts in the third quarter so far, while 63 percent have missed sales estimates, heaping more pressure on margins. British Gas owner Centrica, one of Britain's big six utilities, under fire from politicians for hiking bills, fell 5.1 percent, topping the list of FTSE fallers. It dragged the utilities sector lower after it warned that earnings would not grow this year. Drinks can maker Rexam fell too, down 2.1 percent after it warned on the outlook for trading in Europe, where it generates more than 23 percent of its revenues, according to Thomson Reuters data.