An artist who has pushed a monkey nut for seven miles with his nose and protested in a bath full of baked beans has now set off on his latest mind-boggling stunt.

Mark McGowan, a conceptual artist and environmentalist, began cartwheeling from Brighton to London yesterday to protest about people taking stones off beaches.

He hopes to complete the 57 miles with two 12lb rocks shackled to his ankles and 18 sticks of Brighton rock taped to his face. He reckons it will take two weeks and is likely to require between 43,000 and 48,000 cartwheels.

Mark, 37, of Camberwell, south-east London, said he wanted to make the task ahead "really difficult".

He said: "I like to champion small causes in the name of art and this one is about people taking pebbles off beaches which contributes to the erosion of the Sussex coastline.

"It might not look so bad in Brighton but in other places it is having a damaging effect and it is also illegal."

He said: "It will probably take a few weeks to complete. I am going to go along the old roads, not the A23."

The Argus photographer Simon Dack said: "At the speed he was going, he will be lucky to get out of Brighton in two weeks, never mind get to London, although he said he hopes to improve his technique as he goes along.

"He has even got spare pairs of tights with him which are holding the pebbles to his ankles. It is definitely in the top ten of the most bizarre jobs I have been on."

Mark interviewed 200 people in London and found that 72 per cent of them had taken five or more stones off beaches in England. Most of them said they put them in their garden.

Mark said: "That is a shed-load of pebbles. It is a state of mind as well because it's stealing. Instead of investing in your local economy, these people are coming down to nick your pebbles.

"When I spoke to the council they didn't seem bothered about it. But why? We have had the devastation of the rainforest and the destruction of the ozone layer leading to global warming - when are politicians and governments going to wake up?"

Mark will finish outside Margaret Beckett's office, Nobel House, Smith Square, SW1, where he will deliver the rocks to Mrs Beckett. Mark made a name for himself in 2003 using just his nose to push a monkey nut seven miles from Goldsmiths College to No 10 Downing Street in a protest against university tuition fees.

In the same year he sat in a bath filled with baked beans with two chips stuck up his nose and 48 sausages strapped to his head to advocate the great British breakfast.