Thanks for your concise and relevant answers. We are in this mess because we made a poor investment decision. Since purchase the house has been improved by decoration and bathroom/kitchen renewal, however it is in an area where the 'boom' of 2006 has never been repeated and it is now only worth about 90% of the original purchase price. To re-mortgage today we (or one of us) would need about a 105% mortgage, or put down around a £15k deposit.
Currently the house is let short term and is just about paying for itself.
My understanding of your answers to my questions are as follows.
A1. Yes, a court order to force a sale (an Order for Sale) at market value is one route, but may be expensive to obtain. Is the TOLATA regs the rules that now relate to this type of application?
A2. No, we are jointly and severally responsible, so even if I cough up 50% of the mortgage they could (and would be more likely to!) pursue me for the rest if my ex-mate defaults.
A3. I can't protect myself if he defaults as we are jointly and severally liable, ergo we both get a poor credit rating.
Thanks again for your replies, next stop a read of the TOLATA regs (thanks to
@motorbiking for the link)