Guardian was suggesting his basic will be more or less the same as at present (which they believed to be £220k), but with bonuses he could get to £400k.
As I've said before, I'm always sceptical when the press publish numbers as I'm not convinced anyone would want it out in the open, although I imagine agents share information amongst themselves so they all know what the going rate is. It's not beyond the realms of fantasy that some other agent might blab, but we should always take it with a pinch of salt.
EDIT: Actual quote from the Guardian:
"His previous contact was worth £220,000 a week and he will earn a similar wage, though with performance-related bonuses his pay could reach about £400,000 a week."