As founder chairman of JO Hambro Investment Management in 1986, Richard Hambro developed it into a successful independent concern which, in 2000, was sold to Credit Suisse. At the same time he was a major supporter of British cancer charities. His own last years were marked by a brave fight against cancer, a disease that also claimed the life of his mother.

As a passionate supporter of horse racing, Hambro served as a steward at Sandown and Ascot before being elected a member of the Jockey Club. He was later chairman of Newmarket racecourse. His other great passion was Wiltons, the famous St James's restaurant, which had been bought by his grandfather during the Second World War and remains in the family to this day.

Richard Alexander Hambro was born on October 1 1946, the middle son of Jocelyn Hambro and Silvia Muir. The Hambro banking dynasty traces its descent from Calmer Levy, a young Jewish merchant of Hamburg who moved to Copenhagen in 1778 to marry a cousin and take over his new father-in-law's trading business.

Following Danish custom, Calmer wanted to adopt the name of his native town, but it was misspelt on the tradesman's licence issued to him by the Copenhagen authorities and became Hambro.

Calmer's grandson, Carl Joachim, established a banking business in London in 1839, which flourished particularly in financing trade with Scandinavia. In the sixth generation of the dynasty, Richard's father was a stylish and entrepreneurial chairman of Hambros Bank from 1965 to 1972, when he was succeeded by his cousin Charles (later Lord) Hambro.

Richard was educated at Eton and Munich University before joining the family firm, one of the City's leading merchant banks.

He worked in South Africa and Italy before, in 1973, marrying Charlotte Soames, the youngest daughter of Lord and Lady Soames and the granddaughter of Winston Churchill. They had a daughter, Clementine, who in 1981 enchanted the public as the youngest bridesmaid at the wedding of the Prince and Princess of Wales.

In October 1974 Hambro stood as the Conservative parliamentary candidate in the safe Labour seat of Rotherham.

His immaculate appearance and well-heeled supporters – not to mention his Tory principles – might have inflamed the substantial Yorkshire mining electorate at a difficult political time, but his knowledge of the Turf recommended him to like-minded constituents and ensured the return of his deposit.

After a spell as president of Hambro America (where he installed a putting green in his office), he left the family bank to set up JO Hambro in London with his brothers Rupert and Jamie and his father Jocelyn, who remained a powerful presence in the bank until family tensions were resolved by his departure. The new business operated in the field of investment management and corporate finance.

This reversion to the private partnership format of earlier generations – as opposed to the diversified public company which Hambros Bank had become – was one of the most successful "boutique" businesses to emerge in the reshaped City of the late 1980s. While Richard spearheaded the investment side, Rupert took charge of corporate finance.

After the business had been purchased by Credit Suisse, Richard remained as chairman until his death. He also maintained the family's long-standing relationship with the diamond industry and De Beers through his chairmanship of I Hennig, the leading broker on the diamond bourse.

Throughout his business career, Richard Hambro displayed a strong sense of public service and charitable commitment.

He was treasurer of Macmillan Cancer Relief from 1983 to 1991, chairman from 1991 to 2001, and deputy president from 2001 until his death. Under his guidance the charity grew into an important national organisation, its annual income growing from £3.5 million in 1983 to more than £80 million by the time he resigned as chairman.

He was also a trustee of Bowel Cancer (UK), a governor of the London Clinic and a director of the Institute of Cancer Research.

Hambro supported many other charitable concerns, including St Paul's Cathedral and the South African National Business Initiative, of which he was chairman from 1995.

This latter project, which had been started in the 1960s, helped the education and housing of South Africa's poor, and was endorsed by Presidents Mandela and Mbeki.

In 1995, after his father's death, Richard Hambro moved into the family home at Waverton, near Moreton-in-the Marsh, Gloucestershire, and embarked on a further career in the racing industry.

He became a member of the Jockey Club in 1997. As chairman of Newmarket from 2004, he oversaw the completion of the redevelopment of the July Course.

With his third wife, Mary, who had been the stud manager at Waverton, he bred and raised many winners. Their horse Presenting was the dam of Denman and War of Attrition, both winners of the Cheltenham Gold Cup; and they owned Beechy Bank, the longest-priced winner of a Flat race (100-1) since 1811.

Diagnosed with cancer shortly before his 60th birthday, Hambro's last few years saw a determined, brave but always humorous battle against the very disease which he had done so much to combat.

Richard Hambro's marriage to Charlotte Soames was dissolved in 1982. He married secondly, in 1984 (dissolved 1992), Juliet Grana (née Harvey). He is survived by his daughter and by his third wife, whom he married in 1993.

Published May 7 2009

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