Botanical artist and folk singer. Born in Marchmont House (Scottish Borders), the son of politician Sir John McEwen (1893 - 1962), McEwen was educated at Ampleforth College, Eton and Trinity College, Cambridge. He served with the Queen's Own Cameron Highlanders in Egypt (1950-2) but was soon to publish some of his plant watercolours. This work was interrupted when McEwen and his brother Eck (b. 1935) travelled to the USA, recording folk records, including Scottish Songs and Ballads (1957), and appearing on the Ed Sullivan Show on television. Returning to Britain, he settled in London and, for time, appeared regularly on the Tonight Show. In 1958, he married Romana, granddaughter of the Austrian poet Hugo von Hofmannsthal and, by 1962, had decided to concentrate on painting. McEwen's wide social circle included singer Bob Dylan, writer Robert Graves, model Jean Shrimpton, actor Terence Stamp, the Beatles and members of the Royal Family.
Noted for painting flowers, leaves, fruit and vegetables, his work appears in several botanical texts, together with the collections of the Scottish National Gallery of Modern Art and the Fitzwilliam Museum, Cambridge. His work has been widely exhibited in cities such as New York, Paris and Tokyo.
Terminally ill, with a brain tumour, he died when he threw himself in front of a London underground train. His daughter Christabel married musician Jools Holland.