It matters not who is the first and who is the second applicant - as you say, you are both jointly and severally responsible for the debt so either or both of you can be pursued for the whole of the amount claimed.(posted 7594 days ago)So in answer to your question - the fact you signed in the first box instead of the second does NOT invalidate the mortgage deed - in fact, at the hearing when the repossession was granted, the judge is under a duty to ensure that the mortgage deed is in order otherwise he cannot make an order for possession.