Off-piste skiers are being urged to exercise caution in the Alps after early-season weather that led to dangerously unstable snow-last week, four people died in Val d’Isère and, on Boxing Day, David Robinson, a former Olympic sailing coach, was killed in the same area.

These tragedies come in the wake of a high casualty rate in 2009-10, when 41 people were killed in France alone, compared with a 15-year average of 25. ‘This year, the risks seem even less predictable than usual,’ says guide Henry Schniewind (www.henrysavalanchetalk.com).

‘We have seen slides in places where they don’t normally happen. There are weak layers under the snow pack, and these are unusually hard to spot.’ Some 90% of deaths are caused by ‘slab’ avalanches, and Jean-Pierre Aguillon, technical director of piste security in Val d’Isère, explains: ‘After early snowfall, we had high temperatures, then strong winds, then temperatures of -24˚.

The snow layers haven’t bonded well.’ Nigel Shepherd of the Ski Club of Great Britain advises: ‘Be cautious, get advice and never think you’re an expert. Even with the best equipment, nobody is invincible.’