An external BBC Trust, headed by current board of governors Chairman Michael Grade, "will be the custodian of the BBC's purposes, the licence fee and the public interest," she said. A separate executive board "will be accountable to the Trust for the delivery of the BBC's services." [via Top News Article | Reuters.co.uk]
and the current situation is a 'board of directors' (though probably not quite so formally named, I think Greg Dyke called them his petals) is accountable to the Board of Governors for delivery of services <sigh>.