A short article at the British Library's English and Drama blog on its Evelyn Waugh collection:
The British Library holds an extensive Waugh collection, at the heart of which is Waugh’s incoming correspondence. These letters, dating from 1921 to 1966, the year of his death, were acquired from the Waugh family in 1990 and were selected by Waugh himself (showing him taking some steps towards what we might term ‘self-archiving' and shaping posterity’s view of him). Waugh’s correspondents range from family members to society friends, from friends and acquaintances from the literary and arts worlds and the Roman Catholic Church, to occasional communications, many of which relate to publishing and the business side of writing. The letters vary from extended series over several decades – the most substantial being from Nancy Mitford – to single communications, often congratulating him on his most recent publication.