The Allen Clark Research Centre was a solid-state physics optoelectronics research centre of the Plessey company at Caswell, near Towcester, Northamptonshire, England.

He toured the laboratories and took lunch there, in the company of James Orr and the Earl of Kilmuir.

The Duke unveiled a memorial to Sir Allen Clark.

The site won the 1974 Queen's Award for Technology, for silicon integrated circuits.

[8] The site is now Caswell Science Park,[9] run by Lumentum Technology UK.