Capital gains tax question.

[Roverload]

My mother has sold her garden with planning permission recently, nobody seems to be able to give her a clear answered on water or not she has to pay CGT. She inherited the house 6 years ago, took out a mortgage against the property for £35k which has been paid off using some of the money from the sale. The property was worth £285K, she sold the lend for £160K. She has no plans to move out of the house. Any advice would be most welcome.

Ian