Volunteers are encouraged for timekeeping, tea making, moving tables and putting out food. Contact Hilary Field if you would be able to help on this - 01252 626339.
Some of the country's top cross-country ski racers will descend on London for the London Region Nordic Ski Club's annual 4-hour rollerski race.
Last year some 50 skiers from 8 nationalities took place in the challenge, covering a combined distance of over 2,500km. The overall winner, Tone Sunde of Denmark, covered 121.6km, at an average speed of over 30.4km/hour.
The race welcomes both recreational and elite skiers - and if you don't want to keep going for the full four hours, you can simply complete as many as you can between the start and finish times.
It's particularly good training for anyone taking part in ski marathons or winter triathlons - more details on ski marathons can be found on here - and most of the racers who take part will compete in cross-country ski races on snow.