Alan Clark, after closely reading the first volume of Henry ‘Chips’ Channon’s diaries published in 1967, thought the writer to be “snobbish, arriviste, but intensely observant”. Little did he know, in a then-unpublished entry, Chips considered Alan’s parents, whom he met when Alan’s father Kenneth was director of the National Gallery, to be “chic, snobbish, clever, charming and a touch bogus”. The Channon diaries were the model for Clark’s own. Both men could claim to be among the greatest exponents of the artform in the 20th century, their works full of caustic humour, honest self-reflection, sharp insights and wild indiscretions.

The 1967 volume covered the period from 1934 until Channon’s death in 1958, but was heavily edited to minimise legal action from those still living. Yet Chips started writing his diaries in 1918, and the full manuscript is estimated to be over two million words in length, of which only around 250,000 had been published. Chips didn’t want his full diaries to be made public until 60 years after his death. Now, thanks to the Channon family and the masterly editing of Simon Heffer, we have the first instalment: a 1,000-page tome spanning from 1 January 1918 to the Munich peace agreement in September 1938.

Chips was born into a wealthy Chicago shipping family in 1897 and launched himself into English high society while studying at Oxford. He never looked …