Standing in the sunshine on Old Brompton Street, charting the points of the compass by the movement of the sun, these threats seem a world away, but that's exactly where McGrath's audience are headed. The gaggle of 18 and 19-year-olds are being treated to a day's training in basic survival abroad by McGrath, an ex-soldier and MBE, for Objective Gap Safety. Among essentials about what not to wear and eat, they learn how best to survive a forest fire (you run towards it apparently) and how to save a friend from swallowing their tongue.
All very nice, of course, but is it of any use to your average gap year traveller? "If people think about those sorts of things, they're more switched on," says McGrath. "It gives people confidence to travel."
Most of the information on the course is more mundane, the kind of traveller lore you pick up through more or less bitter experience. It's that practical information that is at the heart of the course, says McGrath, rather than the more attention-grabbing disaster protocol.
"The main advice is, be aware - evaluate what's going on around you, lower your profile, and be confident," he says. "It's common sense."
McGrath is well qualified to give it, with 15 years in the Army, and experience teaching safety courses to journalists, businessmen, and the odd celebrity (Ewan McGregor was one student). All with a dash of bitter experience: McGrath was arrested on gap years in Argentina and Myanmar, and caught hepatitis in South America.
Keeping healthy is one of the biggest challenges for the gap year traveller. McGrath teaches how to protect against diseases like malaria, diarrhoea and hepatitis. And there is some first aid, with McGrath giving a vivid illustration of how effective a belt is as a tourniquet by measuring his pulse before and after strapping it round his upper arm.
He also runs through common treatments, pharmaceutical and home made, including how to ward off dehydration by drinking flat coke with salt. Stuff that you would expect to be general knowledge, but isn't. One girl on our course didn't know that mosquitoes spread malaria, a boy said it was useful to find out that fruit you peel is less likely to give you dysentery.
Most of the people who come on the course are travelling on a budget, so money matters, and McGrath gives tips on haggling, try walking away to see if you can get a lower price. But more importantly he teaches when to know when it's not worth it.
"If you're mugged, you shouldn't take it personally," he says. "See it as an economic exchange, and feel lucky that you're able to walk away from it."
One girl who had been on the course before going to Costa Rica was mugged there at gunpoint. She took McGrath's advice and didn't let it bother her. Her mother thinks that attitude saved her life.
Seeing mugging as an economic transaction is part of understanding how tourists are seen abroad and overcoming it by respecting cultural norms. Some of it is obvious: don't get drunk and visit a mosque, for example. Some of it is less so.
Most of the world's exposure to Western women is through raunchy, by the standards of the village, Hollywood movies, and satellite porn. So it's often necessary to counter that image by dressing and acting respectably at all times, and flaunting a wedding ring (real or fake) at every possible opportunity.
Even as a teacher in Sri Lanka, respectably dressed in a sari, Amanda Briggs, 19, often attracted unwanted attention. "There were all sorts of nasty guys on buses and trains," she says. "I'd flash my [fake] wedding ring and talk loudly about my husband, and it helped."
The course also taught her to trust her gut instincts, and if something didn't feel right, assume that it wasn't. "I'd have this little voice in my head, Charlie's or my parents', saying: no, don't do that, so I wouldn't."
It's the most you can hope for when your children are travelling. As in the rest of life, you can't protect them but you can prepare them, whether on a course like McGrath's or by designing one of your own. That's just common sense.
A one-day gap year safety course with Objective costs £150. For more information call them on 01788 899 029 or go to www.objectivegapsafety.comReuse content