The traditional bobby-on-the-bike image is today being revamped as officers receive electric cycles to help target rising crime in parks.

Instead of pedalling breathlessly after thieves and vandals, officers will now be able to sit back and allow a tiny motor to do the work.

Pcs Jan Cacchione and Jack Shultz will be patrolling 55 acres Holland Park on Powabykes, supplied by Pleiades, Electric Bicycles Centre in Wandsworth. If the scheme is successful it could be extended to Kensington and Chelsea's other parks.

The Powabyke has a top speed of 15mph and does 20 miles to the battery charge — from a standard power point.

Pc Cacchione says: "It's a wonderfully efficient way of getting around without too much effort. You can't help thinking, hey, I'm cycling up hill and I'm not having to do anything."

Inspector Adrian Paterson, in charge of the parks police, says the aim is to use environmentally friendly vehicles where possible. "Even our squad car has been changed to run on liquid petroleum gas," he says.

The three-gear bike costs £500 and running costs work out at 1,5p a mile. The battery has to be changed every 250 charges, however, at a cost of £69.