Britain’s long-held hopes of acquiring for the nation an extraordinary collection of Constable, Gainsborough and Turner masterpieces were dashed yesterday.

The art world had thought that a private collection of 200 paintings and drawings would be going to the Tate.

Instead, it was astonished to discover that it would be going to the Sterling and Francine Clark Art Institute in Massachusetts.

The collection – which includes the most important private holding of works by Constable – was put together by Sir Edwin Manton, a shy British millionaire who died two years ago at the age of 96, having made a £260 million fortune in America.

Brought up a few miles from the Stour Valley made famous by Constable, he was one of the most generous patrons of the arts Britain has ever known. In 1997 he received a knighthood after donating nearly £13 million to the gallery, making him its most generous benefactor after its founder, Sir Henry Tate.

Despite his long residence in the United States, he never took US citizenship. Born in Earls Colne, Essex, he remained fiercely patriotic and once revealed that he collected Constable because the artist represented something of England for him, and reminded him of his birthplace.

Yet his family have now decided that the collection should go to an important institution in America, where he made his money in the insurance market.

In 1933 he went to New York and joined the American International Underwriters Corporation. Less than a decade later he had risen to the position of president and in 1969 became chairman. He retired in 1975.

Michael Conforti, director of the Clark, said: “This magnanimous and visionary gift advances the Clark’s dual mission as both a public art museum and a centre for research and higher education, dedicated to enhancing the public’s understanding of art while advancing scholarship.”

He added that the Manton family was still loyal to the Tate but that because Sir Edwin’s daughter and granddaughters were American citizens, they wanted his legacy to extend to another institution in their own country.

Diana Morton, Sir Edwin’s daughter and head of the Manton Foundation, said: “We knew that the Clark would be excellent stewards of the collection, making it available to future generations of the American public, visitors worldwide, and the scholars and students who frequent the Clark.”

The Tate also missed out on a cash sum of $50 million (£25.4 million) from Sir Edwin’s fortune, which went to the Clark yesterday, one of the largest gifts ever made to a US museum.

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