Managing Partner Nigel Smith is leading a 20-strong contingent in the London South Tough Mudder, staged at Winchester.
The 12-mile obstacle challenge is designed by British Special Forces and involves a series of physical and mental challenges aimed at testing competitors to the limit.
They include military-style obstacles, rugged terrain, steep inclines and water hazards on land described as resembling a medieval battlefield.
“We’ve tackled some tough physical challenges over the years but this has to be right up there as one of the most extreme. I’m facing it with a mixture of trepidation, excitement and genuine fear,” said Nigel.
The Ellis Jones’ team also includes partners Lauren Day, Sean McNally and Nigel Taylor; associates Kate Brooks and Sam Wiley; solicitors including Neil Cook and six trainees.
Since August they have been attending weekly training sessions at Branksome Beach in Poole, with personal trainer Martyn Powell, founder of Stay Slim Avoid the Gym.
Each team member has been issued with a Tough Mudder training programme which covers diet and exercise plans.
Training sessions have included swimming and running in the sea, team-building activities along the beach, running up cliffs and army crawling exercises in the sand.
Nigel said: “It’s been a great team-building exercise as our plan is to stick together and help each other through the obstacle challenge.
“We’ll also be raising money for Help for Heroes adding to the £1 million-plus raised for this fantastic charity by Tough Mudder events.”
Other members of the Ellis Jones’ team include lawyers from Dutton Gregory; Dan Tout, Head of Business Services New Forest at accountancy firm Princecroft Willis and staff from residential and commercial property developer, Ankers & Rawlings.
The London South Tough Mudder is held on Saturday October 25. Donations can be made at: www.justgiving.com/EllisJonesToughMudder/