In 1976, aged 83, he started a new career as an art dealer, in partnership with Hildegard Fritz-Denneville, who had founded Sotheby's Munich office and also worked in the print department. (Their non-commercial approach has brought great success; a German client whom they charged pounds 60 for a drawing they bought for pounds 55 turned out to be a journalist and wrote them up in Handelsblatt.)
Mr Wilder's most enduring passion has been his admiration for the work of John Constable; he has been picking up unrecognised paintings for 70 years. In the late 1960s I remember him looking at a cloud study he'd bought for pounds 50 - it was catalogued as 'English School'. 'It has to be Constable,' he said. 'That brushwork, that sense of movement. Of course, no one will believe me.' He now has roughly 20 'Constables', bought for almost nothing - of which four or five have been accepted by the reigning scholars.
'Study of a Sunset Sky', oil on paper, bought for pounds 50. Right: 'East Bergholt Church', acquired by Mr Wilder for pounds 60 in 1970 and exhibited at the 1971 'Constable and the Art of Nature' exhibition at the Tate Gallery. Below: Copy of a Teniers landscape made by Constable in 1822. Mr Wilder bought it for pounds 22 in 1959. It is included in Graham Reynolds's catalogue of Constable's 'Later Paintings'.
'The Leaping Horse', study for the Constable exhibited at the Royal Academy in 1925, bought by Mr Wilder for about pounds 80.