Not sure quite how to describe this in terms of autobiography. This is the 4th volume and it does cover a later period than the others (mostly) but Osbert Sitwell doesn't adopt the usual linear approach and in some ways this is quite confusing. There are of course huge gaps in the selective narrative, but there are other very detailed sections too. There are some very funny passages, mainly concerning his extraordinary father (and some pathos too, especially at the end). The story about his own intervention, if such it was, in the General Strike is interesting, not least because of the whiff of salons and social political influence, and the account of the early performances of the bizarre but memorable Façade is also worth reading.
The fourth volume of Laughter in the Next Room complements the previous three volumes. This book is witty, enthralling, rich in comedy and deeply moving.