A conceptual artist and environmentalist is to cartwheel from Brighton to London to protest against people taking stones off beaches.

Mark McGowan will carry out the stunt in June and plans 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."

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?"

He said initially he was going to make his journey with courgettes strapped to his head because he believed the pebble-stealers were mainly vegetarians.

But his research changed his mind and he decided to use sticks of rock as props instead.

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.

He has also eaten a fox to raise the plight of crackheads, nailed his feet to an art gallery wall to protest against autumn leaves and rolled from the Elephant and Castle to Bethnal Green singing We Wish You A Merry Christmas in an attempt to get people to be nicer to cleaners at Christmas.