LONDON (Reuters) - Britain's intelligence services are investigating an Islamist Web site that says it is establishing a branch of al Qaeda in Britain, BBC television reported on Tuesday. According to the report, security experts fear a posting on the site, www.alekhlaas.net, declaring "the creation of the al Qaeda organization in Britain" may be genuine. "You don't ignore this sort of thing," Pauline Neville-Jones, the former head of the British joint intelligence committee, told the program. "It may not be a threat from an existing cell... but it does represent a move in the propaganda game and the propaganda game...