I assume that somewhere on the guided ‘Piers and Queers’ walking tour of Brighton, the participants are enjoined to regard, in awe, the Dome — the venue at which Abba, on 6 April 1974, won the Eurovision Song Contest, thus both launching themselves as a wildly successful band and establishing the town (as it was then) as a mecca (probably the wrong choice of word there) for the UK’s swiftly growing gay community.