The natty Englishman can't find a cab in deserted Trafalgar Square. The late-night buses are few, and the Underground has stopped till morning. Unruffled, the gent opens a valise, makes a few minor preparations, and in a jiffy harnesses himself to a giant balloon and is soaring up, up and away toward his flat in Chiswick. No, this is not Roger Moore testing a mini-Moonraker but a former adman named Colin Prescot imagining the practical charms of his quasi-portable, basketless hot-air balloon—the Cloudhopper.

Prescot, who leases larger balloons to his British clients (for promotional use a la the Goodyear blimp), concedes that the commuter model is not for everyone. It will sell for $6,000, and with tank and harness weighs almost 100 pounds (about one-sixth the size of a standard hot-air balloon). Its aluminum fuel tank holds enough pressurized propane for a 60-minute flight, at heights up to 5,000 feet and speeds up to 15 mph. For safety, there's an emergency ejection system and parachute.

But Prescot, 29, the Eton-educated son of a banker, insists the Cloudhopper is more than just an executive shuttle. He plans to market it as "the ultimate dare in a daring sport." Elaborates his partner, Robin Batchelor: "Around you is a couple of thousand feet of nothing, and you're sitting in a floating armchair. You can't help being in awe, but," he admits, "you feel awfully vulnerable."