I started Mutual Admiration Society and then drifted away and never finished it! I really ought to read the whole thing one of these days...

Yeah, the poem is not really *evidence* per se; Sayers could be drawing on personal experience, but she could also just be imagining herself into someone's shoes, "My Last Duchess" style. Anyway, I think the only evidence about the gender of the "you" the poet is addressing is the title? Which could be easily changed so Sayers would have a contribution to the magazine. (It is interesting that she wanted to contribute to the magazine, though.)