The De Haan family, the billionaire former owners of Saga turned philanthropists, have seen their wealth squeezed as they continue to plough their fortune into improving their home town of Folkestone, the latest Sunday Times Rich List has revealed.

It has long been known that Sir Roger De Haan and his brother Peter have been financially backing efforts to regenerate the seaside town since they sold their share in the travel and insurance business for £1.4 billion in 2004.

Yet the latest edition of the Sunday Times Rich List reveals their personal fortune has fallen marginally as they put more cash into projects to revive Folkestone.

The pair have fallen seven places in this year's list.

The siblings' £884 million fortune ranks them at 165th on latest barometer of financial success, having last year taken the 158th spot with a worth of £890m.

The £6m difference is a likely result of their charitable spending to boost the town.

Through their charitable trusts – their financial affairs are now separate although aggregated for Rich List purposes – they have invested substantial sums in education, the arts, wildlife, welfare organisations and Folkestone.

Last year, Sir Roger, 70, who owns the port of Folkestone, gave a £3m donation to his charitable trust, which spent about £7.5m on arts and sports.

But previously, they have injected £18m into sports projects and £42m on the arts and creative industries which has played a major part in the regeneration of the town.

His cash injections are behind the successes of the Creative Quarter, Folkestone Harbour, Three Hills Sports Ground and the Marlowe Academy, Thanet.

The sons of Saga founder Sidney De Haan made most of their money from the sale of the Folkestone-based over-50s travel and financial services group for £1.35bn in 2004.

Peter, 67, runs a wine business and property company.

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