Hi Steve. Really nice that you've joined the Merseypirates forum
Dave Collins is still around on The Scene 102.2 FM. I haven't heard him or The Scene for a while, but he's still on occasionally or so I can gather. I last heard him during the last Christmas holiday.
As regards the Radio Merseywaves music used when a raid was about to happen, I don't know, but I'll ask Bert Williams the next time we speak. If he remembers I'll update it here