A squatter became the lawful owner of a property worth up to £250,000 yesterday ­ although he will have to wait another eight years before he can legally use the front door.

The Court of Appeal ruled that Jack Blackburn was entitled to be registered as the freehold owner of a second-floor Victorian flat in Brixton, south London, because he had lived there for 12 years of "adverse possession". Three Court of Appeal judges reversed a county court eviction order won by Lambeth council, owner of the four-storey block, Granville House. Estate agents estimate the flat is worth between £200,000 and £250,000.

But they ruled that Mr Blackburn, who made extensive improvements to the property, had no legal access to his home. To obtain squatters' rights of access takes 20 years of adverse possession, as opposed to only 12 years for the flat itself. In the meantime, Mr Blackburn will have to continue trespassing on the stairs outside his home.

The problem will either be resolved between the parties or sent back to Lambeth county court. Council lawyers said they might seek leave to appeal to the House of Lords.

The judges said that, in 1983when Mr Blackburn moved in, the fire-damaged flat was regarded as uninhabitable. By the time the council took court proceedings against him last year, he had established 12 years of adverse possession.