Repossession cannot take place without a court order. A court has to be satisfied that there are valid legal grounds for making such an order. In addition to arrears on the mortgage, the following might be cited as providing appropriate legal grounds:
(i) the mortgage was acquired fraudulently (e.g. by overstating the borrowers' incomes) ; or
(ii) there has been a breach of the conditions of the mortgage (e.g. by obtaining another loan secured on the property without obtaining the consent of the mortgage lender); or
(iii) there are arrears on the payments of a second secured loan on the property (irrespective of whether such a loan was obtained with the consent of the mortgage lender and irrespective of whether it's with the same lender).
For general information about repossession, click through the links here:
http://england.shelter.org.uk/get_advice/advic e_topics/repossession
For further advice, use the 'Need more help?' section, at the top right of that page.
Chris
PS: It's not unknown for a mortgage lender to commence the repossession procedure solely because of an administrative error. The Woolwich sent me a 'notice of intent to repossess' several months after I'd paid off the mortgage completely. They'd managed to 'lose' my payment, of over �35,000, somewhere in their accounting system!