An American couple, who bought a £7m house in Chelsea after assurances they would have use of a communal garden, have been unable to prove a legal right to access it, although it is not known if their conveyancing solicitor was aware of the Victorian rules governing it when they made their home purchase.

The Daily Telegraph reported that the couple bought their Grade II listed house in Ovington Square in 2008 mainly because the estate agent had told them they would have access to the private central garden in the square and this would compensate for not having one at their own six-bedroomed property.

Once they had moved in, the garden committee of residents, who oversee usage of the private grassed area which is surrounded by trees, flower beds and bushes, said they could not have keys for access because their house did not directly overlook the garden.

Their address is Ovington Square and they can see the garden when looking left from the front of their house.

The couple decided to sue the committee and the Royal Borough of Kensington and Chelsea, which manages the garden, but in the High Court last week Judge Sir William Blackburne described the couple's arguments as "ingenious but wrong" and said they did not have a legal right to access.

He said the legal requirements of the 1852 Kensington Improvement Act meant that as the front of the house did not face the square in the sense intended, it was irrelevant that the gardens could be seen.

The judge added that, if the case had been proved, it would open the floodgates for other residents in similar circumstances to seek access to the private garden squares of London after they had made a home purchase.

Although the husband involved is a retired lawyer and researched much of the property law involved, the couple have £130,000 legal fees to pay. However, they told the newspaper they would not appeal and intended to stay in the house which they love.