This page says that Warwick has 20% placement rate in marketing:
http://find-mba.com/schools/uk-ireland/england/warwick
That sounds really promising but I haven't been able to verify that by looking at the Warwick website.
There's also Cambridge, which has great pedigree but only placed around 9% of the most recent class in marketing roles.
I can't seem to find any kind of functional placement for Oxford, but this school is on my short list as well.
Any advice?