The Dorset landowner grandfather of one of the "Commons Five" who protested on the roof of Parliament, has applauded her actions.

Sir Thomas Lees, owner of the Holton Lee estate at Lytchett Minster said of Tamsin Omond, "I'm very proud of her."

The 23-year-old was among five well-heeled "Plane Stupid" activists who last week climbed onto the roof of the House of Commons, unfurling banners protesting about plans to build a third runway at Heathrow Airport.

All were arrested after a three-hour stand-off with police and spent 12 hours held in the cells of a London police station after a stunt that hit the headlines.

Sir Thomas, who founded the Holton Lee charity to help disabled people with his late first wife Faith, said he had not known of Tamsin's action in advance but he had been in touch with her since.

"She's the sort of person who realises that she's got responsibility for more than her own life," he said. "She's taking steps to make that responsibility something worthwhile.

"I'm entirely in favour of young people like her broadening their views and really taking part in what is for them something very important," he said.

The daughter of Sir Thomas's eldest daughter Sarah and her husband John, who have homes in Lytchett Minster, London and spend time in Prague, Tamsin was educated at Westminster School and is a church administrator in Primrose Hill.

She is said to be inspired by the Suffragettes and Sir Thomas said he would not be surprised if later on she went into politics. "She comes from a family who have given a large part of our lives to helping other people.

"She's really following in the footsteps of her great-great-grandfather who was an MP around the time of the last century and my father, her great-grandfather, who was a member of Dorset County Council and Purbeck District Council when you had the concern of the individual in mind rather than just party politics," Sir Thomas added.

He added: "We have been in touch with her since to tell her whatever she did she was still loved and still part of the family."