I don't see that as crass at all, not least because female same-sex relationships were never illegal under English law. It was, according to a 1930s Lord Chancellor, 'a vice that was, in his judgement, exceedingly rare' since 'of every thousand women, taken as a whole, 999 have never even heard a whisper of these practices.’ Not sure where he got those numbers from, but 'tennis at Eastbourne' would have been just as obvious as 'confirmed bachelor' to the more savvy reader of an obituary or other profile while simultaneously meaning nothing to the uninitiated.
OK, I was not familiar with the context.