[2] In 1943 he joined Fitzroy Maclean's mission in Yugoslavia (Macmis) whilst on secondment to the Special Operations Executive and appointed as a British Liaison Officer (BLO) to Koča Popović, the most prominent Partisan commander.

In August 1944, the three men agreed the scope and tactics of the Operation Ratweek in central Serbia, which severely damaged German ambitions to withdraw troops from Greece and the southern Balkans.

He served as Assistant Under-Secretary of State from 1966 to 1967 but declined the ambassadorships to Brazil and the Republic of Ireland as he wanted to stay in England.

In 1968 he became Director-General of the British Council, which he remained until 1972, before being invited to resign by Lord Fulton on the pretext of his wife's failing health.

In 1980 he succeeded as eighth Baron Henniker on the death of his 97-year-old father and assumed his seat in the House of Lords.