NTL’s default transparent caching proxy server is still broken! Has been since midday yesterday.
Thanks to Robin Walker‘s excellent Cable Modem Troubleshooting Tips I’ve been able to adjust the browsers on all the machines to get round it.
I realise that what I should have done is changed my Squid proxy on the firewall to use one of the ones that’s still working. That way none of the browsers would have needed changing. Plus I’d still have local caching.
Update: For those looking for a proxy. I have set up an experimental proxy here