I think I might die, every time’. When base jumper Dan Witchalls tells his Danish girlfriend how he feels before launching himself from one of London’s many landmark buildings, it looks like she might knock him out flat. ‘Is it worth it?’ she scowls. ‘Well, obviously it is,’ Dan says, looking more terrified at this moment than he does when contemplating diving off Nelson’s Column or the roof of the new Wembley Stadium. The Men Who Jump off Buildings (Channel 4, Wed 28 Jul, 9pm) shows that, while base jumping is not illegal in Britain, Dan and his ilk can be arrested for trespassing.

The risk of being caught and the thrill of outwitting security systems to get onto a roof is almost a bigger buzz as the jump itself. Since 1981, around 140 base jumpers have plummeted to their ends, including Witchalls’ best friend, Neil Queminet. But despite such figures, Witchalls is clearly addicted to this most out-there of extreme sports. You can see the denial in his eyes when he claims that, if forced to choose, he’d quit base jumping for his girlfriend. Then you see him larking around in a wingsuit (a kind of babygro for golden eagles) and you give their relationship a few more months. His life? Maybe a bit longer.