[1] Thomson is a delegate of the United Kingdom to CERN Council,[2] the Square Kilometre Array Observatory (SKAO)[3] and European Spallation Source ERIC (ESS).

[5][6] From 1992 - 1994, Thomson was a postdoctoral research fellow in the High Energy Physics group at University College London.

In 1994, he joined CERN firstly as a fellow and then as a staff research physicist where he worked on the OPAL experiment.

Since 2000, Thomson has worked at the University of Cambridge as a Lecturer (2000 - 2004), Reader (2004 - 2008) and Professor of Experimental Particle Physics (2008–present).

[12] Thomson is the author or co-author of more than 1100 publications in peer reviewed scientific journals covering a number of major areas in High Energy Particle Physics.