Peer's grandson among the new Greens

Among the five demonstrators is the grandson of a late Labour peer and a female student, who, at the age of 19, is already a veteran of similar but probably not quite so dramatic direct-action campaigns.

The five protesters are members of Plane Stupid, a new environmental campaigning group that has decided to target the aviation industry as one of the biggest contributors to global warming.

The group was formed in 2005 by flatmates Richard George, one of today's rooftop protesters, and Joss Garman, the 22-year-old son of an airline pilot, who has already been named "Britain's coolest activist" by Bliss magazine.

Mr Garman was not involved in today's action, according to Plane Stupid's spokesman.

Mr George, 27, from Wimbledon, with a shock of bright orange hair, has been instrumental in today's action, orchestrating events from the roof of the Palace and giving interviews by mobile phone.

He is up there with Leo Murray, whose grandfather Anthony Greenwood served in Harold Wilson's cabinet and is said to have introduced much of Britain's first clean air and rivers legislation before he was ennobled. Mr Murray regularly speaks on behalf of Plane Stupid, appearing on CNN.

The other male protester is Graham Thompson, another veteran campaigner, who at 34 is the daddy of today's group. He has recently spent his weekends painting a youth club as punishment for his part in a direct-action campaign at East Midlands airport in September 2006, which led to his arrest and conviction for public order offences.

Olivia Chessell, the youngest of today's protesters, was also involved in that campaign. She was pictured today with one arm raised aloft in triumphant salute. She lives with her mother Karen, 59, in East Dulwich.

The fifth protester is Tamsin Omond, who was seen today wearing a green woolly hat. Her last public protest was last month, when she is thought to have worn a penguin costume as part of a party which invaded the ice rink at the Natural History Museum, occupying the site for 20 minutes handing out leaflets and carrying banners proclaiming "BA Fly, Penguins Die". British Airways was a sponsor of the rink.

Mr Garman is a London University politics student who grew up in Radnorshire, South Wales, and whose grandfather invented the bath lift for elderly and infirm people.

In 2003, when he was only 16, he was awarded the Anne Frank Award for Moral Courage for his work with Greenpeace.

He has been described as the "new Swampy" a reference to Daniel Hooper, the dreadlocked eco-warrior who became the public face of the anti-roads movement.

Mr Garman is altogether smarter, both in dress and appearance and in tactical awareness. He often does not take part in protests themselves but acts as the co-ordinator and legal adviser on the ground.

He has appeared on Newsnight and at one stage became so popular in the movement he had to change his telephone number because the volume of calls became overwhelming.

Today's demonstration is separate from the Greenpeace stunt on Monday, when five protesters unfurled a banner saying "Climate Emergency - No Third Runway" on the tailfin of a BA jet at Heathrow after getting through security with fake security passes and reflective jackets. The three men and two women who took part are now on police bail after being arrested. The stunt was a major embarrassment to police and airport operator BAA.