Mortgage not registered by provider

We received a letter in 2008 from our mortgage companys solicitors informing us that our mortgage had not been registered with the land registry and they would pay for re-execution. In the meantime our marraige has failed (we are still in the same house) but there's not a hope in hell of my wife signing anything. Is this an important matter? I'm trying to negotiate a continuation of our interest only payment as otherwise I haven't a prayer of meeting the new rate. Any advice appreciated.

It's not a matter of choice for you or your spouse. When you took out a mortgage, you undertook to take whatever steps as necessary to perfect the banks security. If you fail to do so, the bank can take you to court to compel you, and fix you with the legal costs for that. Even if they don't, all it will achieve is to slow repossession proceedings slightly if it comes to that.

Your wife is equally liable for this with you.

You are depending on the banks goodwill at the moment to get interest only. Don't sign and that goodwill may be non-existent.