[Spike]

Any show on BBC1 or ITV1 gets bigger ratings than shows on C4. If Big Brother moved to ITV1 it would get larger ratings because the only other channel which would be competition is BBC1 but because it's on C4 both ITV1 and BBC1 are competition.

Also I'm a celebrity is advertised to 10m+ who watch Coronation Street unlike Big Brother which is advertised to the 2m+ watching The Simpsons and Hollyoaks..