I am on my way to meet a man called Sticky who is going to teach me how to leap off high buildings.

Sticky is a freerunner, a practitioner of parkour, the street-sport-cum-acrobatics-display whose daredevil moves have helped earn it the supercool status usually accorded only to activities such as base jumping, sky diving and juggling with chainsaws. Sticky has recently been demonstrating his techniques to physical training instructors from the Royal Marines - and now he's going to show me the same manoeuvres.