There is something a little dated about this description of someone’s clothing, but I liked the ‘glee-singing competition’.  I had a vague idea of ‘glee’ as a kind of song, but looked it up to find out more:
‘A glee is an English type of part song spanning the late baroque, classical and early romantic periods. It is usually scored for at least three voices, and generally intended to be sung unaccompanied. Glees often consist of a number of short, musically contrasted movements and their texts can be convivial, fraternal, idyllic, tender, philosophical or even (occasionally) dramatic. Their respectable and artistic character contrasts with the bawdiness of many catches of the late 17th century, which were thought inappropriate in female company. Although most glees were originally written to be sung in gentlemen’s singing clubs, they often included soprano parts—which were sung by boys (church choristers) in earlier years, and later by ladies who were often present, although only as guests.’
‘Your present get-up seems an unhappy compromise between the correct wear for a theatrical party at Maidenhead and a glee-singing competition in a garden suburb.’
Sources: Evelyn Waugh, Brideshead Revisited: The Sacred and Profane Memories of Captain Charles Ryder (Harmondsworth: Penguin, 1968 (1945)), p. 43 and Wikipedia
