His career in fusion research spanned forty years, encompassing work in the UK first at Harwell and then at Culham, and abroad as far afield as Russia, China and Japan. He was the driving force behind the very successful spherical tokamak approach to fusion, pioneered at Culham with first the START and now the MAST experiment.

He was a prime mover in the European and international fusion research scenes including membership of the top committees for Europe's JET experiment at Culham. He was held in the highest regard by the international fusion community.

He was born on 27 May 1941 in Douglas, Isle of Man. He gained a First Class Physics degree and a PhD at the University of Manchester. He was Fellow of the Institute of Physics and was elected a Fellow of the Royal Society in 1994. He was also a Vice-President of the Institute of Physics and Chairman of the Board of Institute of Physics Publishing Board.

Derek was also a keen horticulturalist. He is survived by his wife and daughter.

Expressions of regret may be sent to martin.obrien@ukaea.org.uk