In the late 1960s McCarthy was a driving force behind the newly formed Salaried Architects Group (SAG) which campaigned to modernise the RIBA.
Fellow SAG member Sam Webb said: ‘Maurice was an extraordinary character.
‘He modernised the RIBA and was one of the first, if not the first, to recognise the threat that the newly constitutionalised ARB was to the RIBA,’ he added.
McCarthy was also responsible for revising the RIBA Code to include an obligation for architects to consider the interests of the client and public.
His funeral will be held this Thursday (28 February), at Amersham Crematorium, Buckinghamshire.