Dewhurst, previously head of public relations at Russia's biggest firm Gazprom Marketing and Trading, has joined the financial PR agency as a senior consultant.
He joined Gazprom from British Nuclear Fuels and has worked at Railtrack and the Chemical Industries Association, as well as serving as UK CEO of Weber Shandwick.
Dewhurst said: ‘I don't think there are any in-house jobs out there that would match either the nuclear industry or Gazprom in terms of the challenges and issues they bring. College Hill offers a great opportunity to go back to a consultancy environment and help other firms facing these issues.'
He will work in partnership with fellow senior consultant Geoff Potter, who previously led GlaxoSmithKline's global corporate communications function for 23 years.
Dewhurst added: ‘There are some fantastic corporate affairs directors out there, but even the very best of them will sometimes face challenges that they haven't dealt with before. Geoff and I will be looking at communications from the perspective of what the comms director wants, rather than just what an agency typically offers.'
His role will also see him liaise closely with managing director Donna Zurcher and founder Alex Sandberg.
Dewhurst noted the depth and breadth of work College Hill does for heavyweight clients across its public affairs, public policy and branding and design arms and said it aimed to win more top clients in the corporate space: ‘Certainly we are very ambitious in terms of growth and winning more FTSE clients.'