A five-hour stand-off between the chair of a residents' association and police took place 50ft above Chelsea - when he climbed a giant crane in protest against security at a new academy school building site.

Respected Michael Gall, 61, who has lived in the area for more than 35 years and is chairman of the Westfield Close Residents' Association, pulled the dare-devil stunt at the Chelsea Academy construction site in Lots Road over concerns about security on the site, which he says attracts borough youths at night.

Just after 8am, police were called to Tetcott Road where Mr Gall - a soft-spoken Scotsman known for wearing a distinctive hat - had scaled the wall and shimmied up one of the giant drilling rigs on site.

Clutching at muddy wires and precariously balanced on a thick cable more than 50ft up, he cut a tiny figure as the Lots Road power station towers loomed behind him in the gloom on Monday morning.

He said: "I'm doing this because we've lost our rights. They are coming for me. They've got one of those crane platforms. I'm going to have to climb higher now."

He has carried out similar outlandish protests in the past and once scaled the Heatherfield School of Art to complain about its move to Lots Road earlier this year.

It took another three hours before Mr Gall came down from his perch, before being taken to a ward of the Chelsea and Westminster Hospital in Fulham Road, Chelsea. No action has been taken against him.

Since 2006, Mr Gall has been an outspoken critic of plans to build the new secondary school in Lots Road, Chelsea.

A Kensington and Chelsea Council spokesman said: "We are aware that there is some opposition and people who have been implacably opposed to the school. But the reality is that it is now being built and we look forward to its opening in September 2009."

A spokeswoman for construction firm Wates added: "The site security is in accordance with policy. The hoardings are of regulation height. However we will be investigating the incident to see if there's more that can be done to prevent a reoccurrence."