The great escape - if you're in shape

Some women just aren't the right size for climbing over the spiked railings after they've been locked inside Kensington Gardens, or at least the one I encountered on Saturday night wasn't. Her male partner and dog had already jumped clear; she was prone along the top of the spikes, and hysterical. The man was gamely trying to lift bits of her free, while the barking spaniel, who thought it was all a terrific game, was up on its back legs, scrabbling at the chap's groin and putting the whole operation in jeopardy.

I had a shot at helping the woman but she was too heavy, so I dealt with the dog instead. The episode ended satisfactorily but I'll bet she gave that chap hell all the way home.

Then blow me if 10 yards further along there wasn't another prisoner, this time a young male trying to lower his bicycle down over the spikes; he also was in imminent danger of impalement, so I took the bike from him, and very heavy it was too. He was effusively grateful but I really feel my days of hefting bikes and women around are drawing to a close. From now on I'm giving inner-city parks a wide berth in winter.

South of the river we're more organised. Richmond Park locks its gates at night but that's to contain deer and cars. Discreet escape routes are left open for pedestrians and cyclists. And if a visitor misjudges how long it takes to get to any exit in Kew Gardens before closing time, they'll find a phone there which connects with the gardens' private constabulary. Who send someone round to shoot them. (Only kidding.)

On a more parochial level, though, we're not quite so efficient. It took us for ever to get the lock fixed on the door to Old Palace Lane allotments. These are walled on two sides, there's a railway embankment on a third, and the fourth is railings swamped by nettles during the growing season. The only way in or out is via the Alice in Wonderland wooden door set in the 10ft brick wall. As the lock was malfunctioning for weeks, even the most mundane horticultural task was imbued with an element of risk.

Unless you've got a really comfy shed with a supply of liquor, a good book and a torch, there's not much to do on an allotment if you're locked in after dark. And mobile phones are only a godsend if your allotment partner ever turns theirs on. I was on the point of phoning the police but the thought of ending up in the Richmond and Twickenham Times gave me pause: I'd rather risk my neck going over the wall via the Bramley apple tree than have to walk around town in a balaclava and dark glasses. Desperation made me have one last go at the lock. And lo, dear reader, it yielded.

So now you know why I help others who find themselves similarly deprived of liberty. But from here on in, only the lightweights.