The Sipp provider was taken over in April by two private investors Richard Wohanka and Phil Smith.
Mary Stewart, sales and marketing director is leaving the firm after seven year. The firm said it would not be replacing her directly as marketing would be looked after by Tim O'Connor. Mr O'Connor was appointed by the new directors in April and is managing director of propositions and distribution.
Bob Adams will join the firm as managing director of infrastructure. He joins Hornbuckle Mitchell from UBS Global Asset Management where he worked as global chief information officer.
Jo French will be joining as managing director of operations and client experience, reporting to Mr Adams. She joins from rival Sipp provider Pointon York where she worked as managing director.
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Mr Adams joins Hornbuckle Mitchell, a corporate member of the Institute of Financial Planning, with immediate effect while Ms French will join in Q3 2013. Both appointments are subject to approval by the Financial Conduct Authority.
Phil Smith, chief executive of Hornbuckle Mitchell, said: "I am absolutely thrilled that Bob and Jo will join Hornbuckle Mitchell to complete our senior team. Bob's vast experience of delivering both cutting edge commercial technology solutions and global business change in complex environments is perfectly suited to the challenges of our marketplace over the next 3-5 years.
"Equally, Jo will greatly strengthen our ability to deliver exceptional service to our distribution partners and pension scheme holders. Both are proven change agents and winners, and we now arguably have the most experienced senior management team in the UK Sipp industry."

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