Despite being educated at both Eton College and the University of Cambridge, he was a supporter of the comprehensive school system, fighting for the rights of working-class children and teachers.

[5] Soon after his return he joined both the National Union of Teachers (NUT) and the Communist Party of Great Britain (CPGB), becoming a lifelong member of both organisations.

Fighting for higher wages and better conditions for British educators, he was repeatedly (and unanimously) elected the leader of the Middlesex Teachers’ Panel, which under his leadership was frequently successful in its negotiations with the County Authority.

[11] Following the outbreak of the war, he emerged as a senior figure in the NUT and was appointed leader of the head office at Hamilton House, the organisation that prepared the evacuation of teachers and young children from cities likely to be bombed by the German airforce.

[11] Operation Pied Piper, assisted by a team headed by Giles and carried out by 100,000 teachers and parents, successfully evacuated over three million British children to the countryside without a single fatality.

[11] This evacuation was the single largest mass migration of civilians in British history, and its success would see Giles's position rapidly rise within both the NUT and the CPGB.

Although Giles personally felt that the Act did not go far enough to address issues concerning income inequality,[17] he and many other similarly-minded education reformers were satisfied enough with its provisions to throw their weight behind it.

[11] Giles was also selected by Butler to tour and give speeches at sites throughout the UK where Allied troops were preparing for the Normandy landings (D-Day).

[11] After World War II was over, Giles's position as president of the NUT allowed him to influence the direction of Britain's post-war educational reforms.

A number of MPs, especially the Conservative backbencher John Eden, took advantage of the safeguards against libellous speech in parliament to slander and attack Giles, leading to partial bans on communists joining certain teaching professions.

[7] These McCarthyist attacks and slander campaigns against British communists led to many teachers losing their jobs, including Margaret Clarke, John Mansfield, and J.T.

[2] For many years they lived in Chiswick, including a period of time spent sharing a house with the trade union official J. O. N. Vickers and his wife Freddie.

[2] In 1968 both he and Max Morris, who later became the second communist president of the NUT, endorsed the executive committee's decision to oppose the Warsaw Pact invasion of Czechoslovakia.