Miles Blackwell, 56, and his wife Briony, 10 years younger, died within three weeks of each other only months after retiring from the family publishing business to breed rare hens and pigs in the Oxfordshire countryside last year.
But although the childless couple came to a tragic end, their generosity has now made a small charity into one of Britain's biggest.
It was announced yesterday that the couple have left the Tubney Charitable Trust – which they set up in a small way in 1997 and named after the village in which they lived – a bequest of £30m. It will also be given a further £20m from another family trust. The gifts have made it one of Britain's 30 largest charities in terms of income from donations.
The couple had only just cashed in their £65m stake in the Blackwell publishing empire when Mrs Blackwell died suddenly last August from a rare condition that made her sensitive to chemicals. Shortly afterwards, her husband died after a massive haemorrhage.
Jonathan Burchfield, of the solicitors Nabarro Nathanson, a trustee, said it was very rare to have such a large charity created in one move. "There are charities that are bigger in terms of their funds, but they have normally been around for quite a while," he said. "The challenge now is to spend this money over the next 10 years or so in ways of which they would have approved."
The trustees will look at funding research into the multiple chemical sensitivity that killed Mrs Blackwell. Other likely beneficiaries include the Rare Breeds Survival Trust.
The Blackwell publishing empire has descended into acrimony since Mr Blackwell's retirement, with rival family factions arguing over a proposal to sell the business.