LONDON, April 29 (Reuters) - The pound edged lower against the dollar on Wednesday, as a stalemate over peace talks to end the Iran war, together with caution ahead of a series of major central bank decisions, including the Bank of England, kept investor risk appetite in check. Sterling has recovered all the losses incurred by the Iran war and is sitting on a gain of 2.1% for April, making this its strongest monthly performance since last August.