I'm always apt to get stuck in one corner, and it's apt that it was the SW corner, just like A Hearer. One is apt to forget that in the past quite a few Listener puzzles consisted of little more than an apt quotation round the edges, so this was an apt and rather nostalgic reminder of past Listener styles. As Upsetter aptly says, there was no way of proving that you'd got the theme, but I'm apt to forgive that when it's a relatively easy and unambiguous solve. I'm apt to forget names, but if Apt is a new setter, he clearly has considerable aptitude, so it's only apt to thank him or her for the puzzle.
(Contrary to what some believe, I - and most others here, I'm sure - don't rush to my gadget to register my apparent success with the Listener crossword, but I definitely have to be first to get the bad jokes in!)
PS Recommend the Chalicea IQ - it's a beauty.