What are they? Zipped bags on a belt. Extremely practical.

Worn back or front? Front for market traders and pedestrians. Back for cyclists, climbers, fell runners and surfers.

Surfers? There's a waterproof one: so your mobile's not nicked off the beach. Made in Australia, that one.

Good for security? Better than a shoulder bag or ordinary pockets. Not as good as a money belt or a neck pouch worn under clothing.

Cheap and garish? Every merchandising range from the Simpsons to Lord's cricket ground has a tacky nylon bum bag for less than a fiver: best worn with white socks, sandals and a loud baseball cap.

But I want something stylish: Driza-bone do one in leather for £90. Lowe, North Face and Berghaus do well-designed models for walkers, runners and cyclists from £10 to £33.

The latest wheeze? Models that open into a light rucksack. Also bum bag first-aid kits and neoprene bum bags for anglers, worn chest-high above the waders.

Points to look for? Wide belt with secure, adjustable fasten ing. Shaped lumbar padding for cycling and running models. Lined interior, so sharp seams edges don't slip under your finger nails. Internal compartments. Zips that work smoothly. Pouches for drinks bottles, if you're going to be working hard.

So why's it called a bum bag? Something to do with where you wear it: the Americans call them fanny packs, if that's any help.

What's the alternative? Bulging pockets, bouncing backpacks, losing things.