Chocky was John Wyndham's last published novel before his death in March 1969, so when Penguin published it in paper- back the following year, it also reprinted its entire backlist of Wyndham titles, with cover illustrations by Harry Willock.

Willock had worked at The Sunday Times with Alan Aldridge, and when the latter left in 1965 to become Penguin's art director for fiction, he invited Willock to join him as his assistant. So Willock also made the move and was soon designing covers for reprints of Jules Verne's Journey to the Centre of the Earth and some of H G Wells' sf novels.

Willock's ghostly line drawings on coloured backgrounds began appearing on Wyndham reprints in 1968, but were partially hidden beneath the title and author's name which were stamped across the drawings in large black capitals. Like other covers that year they were also blighted by 'A PENGUIN BOOK' panic tops so these 1970 covers were a significant improvement, with no panic tops and – apart from The Chrysalids – a better separation of the artwork and typography.

On leaving Penguin in 1968, Aldridge set up his own graphic design studio called INK and Willock again went with him, but continued to illustrate the remaining Wyndham covers (the boy on the cover of Chocky is Willock's son) for Aldridge's replacement at Penguin, David Pelham. As with Franco Grignani's sf covers which were also appearing at that time, Willock's Wyndham covers are at their best when seen as a set.

The six novels shown above were also available as a boxed set, The Penguin John Wyndham, in a slip-case featuring the drawings on the covers of the books within. The set was reprinted with a red, blue and silver slip-case three years later.

In addition to the six novels, Wyndham's three collections of stories were also reprinted with artwork by Harry Willock.