John David Lawson was born on 4 April 1923. He was educated at Wolverhampton Grammar School before going on to St John's College, Cambridge to study for the short (two year) Mechanical Sciences degree, including a special wartime radio course. He graduated BA in 1943 and then joined the Telecommunications Research Establishment, Malvern, where he was assigned to work on microwave antenna design under D.W. Fry, as part of the ongoing work on development of radar. At the end of the war Lawson continued to work at Malvern, although in 1947 he was made a member of the staff of the Atomic Energy Research Establishment (AERE). He undertook experimental work with the new 30 MeV synchrotron.

In 1951 Fry’s group was transferred to the General Physics Division of the AERE at Harwell. Lawson was assigned to working on the klystron, a device for producing high-power microwaves, in a group led by Peter Thonemann. Thonemann was also in charge of the ZETA (Zero Energy Toroidal Assembly) fusion work, and it was through Lawson’s association with Thonemann that he became interested in the topic of nuclear fusion. Lawson also worked with the 1980 MeV cyclotron and on early accelerator proposals. He remained on the staff of the AERE to 1961, spending 1959-1960 as Research Associate at the W.W. Hansen Laboratories at Stanford where his work included the study of the properties of caesium plasma.

In 1961 Lawson transferred to the newly established National Institute for Research in Nuclear Science, based very close to Harwell, an institution shortly to become the Rutherford Laboratory and then the Rutherford Appleton Laboratory. He continued his work on accelerators and led the project to build the Variable Energy Cyclotron (for AERE Harwell). He had responsibility for building up the superconducting magnet programme and retained an interest in new accelerator concepts. In the 1970s he moved onto the study of very high current beams and in 1977 his book The Physics of Charged Particle Beams was published (second edition 1989), which became a classic textbook on particle accelerators. In 1975-1976 Lawson returned to fusion research with a two year sabbatical at the Culham Laboratory, working on a design study of a conceptual fusion power reactor based on the reversed field pinch principle.

He returned to the Rutherford Appleton Laboratory in 1977 where he continued working on free electron lasers and accelerator design, and also played a leading international role in promoting and critically examining ideas for future accelerators. In the early 1980s he recognized the potential that high-power lasers could have for particle acceleration, and set up a small research group in laser plasma accelerators. He retired in 1987.

Lawson was awarded the University of Cambridge Sc.D. in Physics in 1959 and made a Fellow of the Institute of Physics in 1970. In 1983 he was elected a Fellow of Royal Society 'for his contributions to the field of applied electromagnetism, in particular the physics of charged particle beams and high temperature plasmas'. He is particularly remembered for the Lawson Criterion, a general measure of a system that defines the conditions needed for a fusion reactor to achieve net power. Formulated in 1955, it was first published in 1957, in ‘Some criteria for a power producing thermonuclear reactor’, (Proc. Phys. Soc. vol. 70, pt. 1, no. 445, B, 6-10).

Lawson died on 15 January 2008.