Nicole Barber-Lane (Myra McQueen), Loui Batley (Sarah Barnes), John Pickard (Dom Reilly) and Junade Khan (Ash Roy) all agreed to take part in the 26-mile trek across London on April 26.
Speaking exclusively to DS about her challenge, Barber-Lane joked: "I'm hoping this year's going to be better than the last! I didn't know where I was going or what I was doing! I didn't realise that you had to walk a mile before you got to the start line. So I started completely on my own last year and it took my 7 hours, 58 minutes and 58 seconds.
"I said I'd never do it again, but I'm a glutton for punishment," she continued. "I was that slow last year that the wagon that takes down the direction and mileage signs was right behind me! I was begging them not to overtake me. By this point, the water stations had been taken away as had the barriers, too!"
Barber-Lane is hoping to raise £2,000 for her chosen charity The Prostate Cancer Charity, an organisation of particular significance to her as her father underwent a lifesaving operation the day before the 2008 race after being diagnosed with a severe form of the condition.
Of the illness, she added: "It's something that a lot of people don't understand. It's so complicated, yet it's so common."
Pickard and Khan are running for The Leonard Cheshire Disability, while Batley is raising money for Whizz-Kids.
Their sponsorship pages can be found by clicking here.