Huckster,

Thanks for the link, I must've missed that one.

My current mortgage provider (Northern Rock - funnily enough!) is aware that I let the property and had given consent to let two years ago. They said it fine, unequivocally, and I paid the £250 one-off fee.

There was a comment in the link that said it is not illegal to let a property on a residential mortgage; with this in mind (my friend is not going to get imprisoned!), I am going to approach new lenders asking for a residential mortgage with consent to let and see what rates and fees apply; and if they are comparable to current buy-to-let mortgages available.

Rob