Well... thanks to all for trying it, and Lumen, I'm so sorry you didn't finish it. Doing the grid fill I was simply aiming to fill the grid with as few double- or triple-unchecked as possible, so I didn't notice that there were so many of the same letter. It didn't help that an early tester realised that I'd gone the wrong way down a one-way street and I had to rework the entire bottom left corner of the grid. The aim of a crossword setter is to make the solver feel they've entered in a fight with you and won fairly, without them realising you've let them win... if you couldn't finish it, I failed at that aim, so I'm really sorry to have broken your streak.
Well done to those who solved it - very, very good work. It turns out it was quite hard. As ever, it's interesting seeing how people get stuck. I'm fascinated by the fact that I was seriously worried it was too easy when I submitted it. Just goes to show. I won't be a regular IQ setter - they're just too bloody hard - but I do have ideas for perhaps occasional ones. And you'll see me in the Guardian's Cryptic and Genius slots too.
Take care, all.
H/S
PS Jack Aubrey, remind me which of my (three!) colleges you're a past member of?! I'm ashamed to say I've forgotten.