On his return to civilian life, Donaldson became associated with the set surrounding Princess Margaret, Countess of Snowdon, and worked as a theatrical producer.

He established himself as a central player in the British satire boom of the early 1960s, as co-producer, with Donald Albery, of Beyond the Fringe (1960), and of dramatisations of J. P. Donleavy's The Ginger Man (1959) and Spike Milligan's The Bed-Sitting Room (1963).

In 1968, Donaldson received a substantial inheritance, and in 1971 he left Britain for Ibiza, where he imprudently spent his last £2,000 on a glass-bottomed boat.

[6] Donaldson's biographical survey of roguish Britons through the ages, Brewer's Rogues, Villains and Eccentrics (2002), has been described as "a breathtaking triumph of misdirected scholarship".

[8] The phenomenal success of the Henry Root books, especially the first, enabled Donaldson to resume his earlier chaotic lifestyle, and in the mid-1980s he began using crack cocaine.

He later remembered that "sex, whether in company or not, has been the only department in life in which I have demanded from anyone taking part the very highest standards of seriousness.