Bell, who left Brunswick last Friday after nearly ten years with the firm, will replace industry veteran and Old Mutual director of corporate affairs James Poole.
It is understood that Poole, who has been with Old Mutual for five years, is to retire after Bell's arrival in September.
Bell worked in equity sales for SBC, the forerunner of UBS, before joining Brunswick in 1995. In 2000 she helped set up Brunswick's European team, which is led by Brunswick partner Rurik Ingram. Her clients include fashion house Gucci, whose brief Brunswick took on in October last year, and French construction material giant Lafarge.
Bell said her affinity with Old Mutual began after a one-year secondment to Cape Town in 1998, working for the firm's smaller South African rival Sanlam Financial Services.
She was approached for the Old Mutual job through headhunter Taylor Bennett.
Bell will have overall control of Old Mutual's media relations, internal communications and investor relations, which is likely to involve any future acquisitions.
Old Mutual said in May that it was in talks to buy Stockholm-based insurance firm Skandia and reportedly has a £1bn war chest for the acquisition. Old Mutual would use a successful deal as a springboard to expand its operations outside of South Africa. Skandia already has a life insurance business in the UK where Old Mutual is keen to extend its business.
Bell declined to comment on the Skandia negotiations or her plans for Old Mutual's ten-strong PR operation. She also refused to rule out a review of the company's relationship with College Hill Associates, which was originally appointed on a £600,000 brief in 1998 to handle Old Mutual's demutualisation and stock market listing.
'It is premature for me to comment on these things before I get my feet under the table,' Bell said. 'This is a company from a complex country with complicated issues such as the challenge of black empowerment and how to tackle this properly.'