Sansom followed up his win in Humberside by travelling west to Minehead with Clive Jenkins after regular Dartford-based co-driver Phil Wells was forced to pull out due to his other working commitments.
And Sansom was on the pace from the start, only dropping a handful of seconds over the early stages to event favourite Simon Chapman in the more powerful Vauxhall Corsa.
Snowy conditions in the higher altitude forests made the track very slippery and many crews spun during the race.
The forestry stage is unique in that it incorporates two tarmac stages over the famous Porlock toll road. Although this should have been to Chapman's advantage, Sansom made a decisive tyre choice which left his rivals struggling to keep up with him on the slippery hill climb.
This gave him a lead of eight seconds, which he successfully defended over the last forest stage to claim an unexpected win against the more powerful machinery of his rivals.
And Sansom is also hoping for success in the Roger Clark Award where the winner will be provided with a budget of £50,000 to further their career.
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