Cool, well, irregardless, Blizzard appear to think it's Virgin Media's issue. Their network people have told me
" Looking into the Network Diagnostic files that you created for us shows a potential cause of your problems too. If you can check the WinMTR test that you ran, we can see that you are experiencing packet loss within the Virgin Media network reaching Amsterdam. I would suggest that you reach out to them as well and ask them to look into this for you, and consider including the WinMTR result to help them pinpoint where to focus the investigation."
Clearly, I have a problem somewhere. I would just like to know where. Because, I can't play