In 1824 Samuel Palmer met a highly eccentric and little-known artist called William Blake. As Palmer later recalled, ‘He fixed his grey eyes upon me and said “Do you work with fear and trembling?” “Yes, indeed,” “Then you’ll do.”’ This brief exchange has the too-perfect air of careful buffing, but whether or not it happened that way, the meeting with Blake was to change Palmer’s life. It was also to influence a great swathe of British art.

The bloodline that started with this meeting runs through the Pre-Raphaelite Brotherhood, John Ruskin, Paul Nash, Eric Ravilious, Graham Sutherland, John Piper and a host of other pastoralists. The same blood can also be found in the veins of W B Yeats and John Berger (though here in a tainted form, since the latter described Palmer’s pictures as ‘landscapes