Judgment giving 90% of house to woman who paid mortgage for 13 years has implications for millions of unmarried couples in England and Wales.

A Supreme Court judgment this week, which awarded Patricia Jones the overwhelming share of an Essex bungalow, has redefined the property rights of unmarried couples and has triggered calls for legal reform. Patricia Jones was challenging a Court of Appeal ruling which gave her former partner Mr Kernott an equal share of the home's value.

The decision by 5 Supreme Court Justices makes it clear that even though a property is registered in joint names , judges are permitted to substitute a fairer division of the shares in the property.

In this case, the couple bought a house in 1985 in joint names and took out a joint mortgage  The parties separated in 1993 after sharing the home for 8 years. When Mr Kernott moved out, Ms Jones continued to pay the mortgage.

The highest court in the UK decided Leonard Kernott was entitled to only 10% of the property's equity – which was £240,000 in 2008. The difference in value between the ruling of the Supreme Court and the Court of Appeal decision which was overturned was around £90,000.

The ruling decided that a court  may decide what is a fair division of the net equity of a jointly owned property where the intentions of the owners as to division of ownership are not clear.

The judgement applies to unmarried couples in England and Wales. This could alter the legal landscape for unmarried couples arguing over property after separating. It is thought that there are more than two million unmarried couples living together in England and Wales; almost 50% of children are now born outside marriage.

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