John could you have this link ready to click when your radio stream drops.
http://tools.virginmedia.com/cgi-bin/ping.pl?bbc.co.uk
Either with or without the router attached. The reason I ask and I should have mentioned in my above post, so apologies. Is that you were informed of "ping loss", however, a loss of packets "ping loss" are not apparent in the results you have posted back.
So if we can capture any packet loss when you lose connection to the radio broadcast then we can point the finger at a VirginMedia network issue.