Just found after finishing post below: Ronald Searle draws Lasdun! And in the sylvan setting of the Hallfield estate, no less. From here, which also notes that Searle lived in one of Lasdun's early international style works, this house in Paddington. Weird, as one can't think of a less Modernist draughtsman than Searle - all those tortured, Gothic lines and prickly spaces, even in this drawing. Maybe this implies that Searle didn't like places like St Custards. The reason they look sick is because they are, however much that sickness might be intriguing.