Brian said he's a grandad, when he was awarded the honorary fellowship at LJMU, not long before he was offered to be LJMU Chancellor.
I think the video is not available anymore, but I remember it was on his 60th birtdhay (that is 19th july 2007), and he said something like "I'm a parent too... actually, I'm a grandparent now". Probably not the exact words, but it was pretty much like that.