I don't have the figures, but it's possible that those are both correct figures referring to different things. For example, it's possible that 8% of those who apply will go on to successfully take it (i.e. go to study MORSE at Warwick) and the remaining 92% may or may not get an offer but choose to go elsewhere, or don't make the grades, or don't get an offer at all; whereas 70% could, for example, be the offer rate, i.e. be the percentage of students who apply that get an offer, whether they accept it or not.
As above, I don't have the figures but this sounds similar to a course I was interested in UCL, which, at the time, had like 1 place per 11 offers, i.e. about a 9% "acceptance rate" but gave out way more offers than that and wasn't actually super competitive, as obviously not everyone who get an offer would accept it. I have heard, for Maths at least, that Warwick gives out quite a few offers but with quite high conditions, so this could be an explanation for the discrepancy.