Hilsum was elected a member of the National Academy of Engineering in 1983 for the inventiveness and leadership in introducing III-V semiconductors into electronic technology.

Hilsum entered Raine's Foundation School in 1936 as the middle of three brothers, leaving in 1943 after being accepted into University College London, where he did his BSc.

In the 1990 Queen's Birthday Honours, he was appointed a Commander of the Order of the British Empire (CBE)[4] for "services to the Electrical and Electronics Industry".

[7] He has served as a corporate research advisor for various entities, including Cambridge Display Technology, the European Commission and Unilever.

[13] While working for the Ministry of Defence, Hilsum helped develop commercial applications for gallium arsenide, and was responsible for creating the UK's first semiconductor laser.