A Kidlington family firm is seeking millions of pounds of taxpayers' money in compensation after a farmer and his wife gained possession of 58 acres of the company's land through squatters' rights.

The European Court has already ruled the UK Government has broken the Human Rights of the company, Pye (Oxford), by failing to change the law to protect registered landowners.

Today the European Court's Grand Tribunal, consisting of 17 judges, will hear the British Government's appeal against that decision. If it loses, the question of how much compensation, paid from taxpayers' money, should be due to Pye.

Managing director of Pye (Oxford) Graham Pye, who has described the ancient law of adverse possession as "legalised robbery" says the land in Berkshire has been valued at £10m. With planning permission it could be worth £21m.

He said: "I hope we shall hear a ruling in February."

He added the case had been "very expensive" for the company, which was founded by his father with £5 borrowed from his grandfather, and now now employs 30 people.

Housebuilding company Pye (Oxford ), founded in 1927, bought 58 acres of potential development land in the mid-1970s and registered its ownership at the Land Registry.

Pye gave grazing rights to neighbouring farming couple Michael and Caroline Graham until 1984. Then it gave notice that it wanted the land back for possible development. However, the farmers continued to use it and in 1997 they registered a squatters' rights caution at the Land Registry, having occupied it for the 12 years necessary to claim it under the ancient law of adverse possession.

Mr and Mrs Graham won a High Court case when Pye tried to reclaim the land, but this was overturned in the Court of Appeal.

Mr Graham died in 1998 but his wife, who lives at Henwick Manor, the farm bordering the fields in question, is now in possesion of the land gained under the old law. She was unavailable for comment.

The House of Lords ruled once again in the squatters' favour and Pye took the case to the European Court in Strasbourg.

Seven European judges ruled by four to three that the British Government had breached the Human Rights Act by failing to change the law to protect landowners' rights.

A change in the law of adverse possession in 2002 now offers some protection to registered owners of property, but it came too late to help Pye and it is not retrospective.