Thanks tjj. Not that difficult to get to... as Welsh circles go. A bit of a short, but sharp walk up a small hill from a green track at the end of a dead end tarmac road from Llandrillo. A pretty remote feeling nonetheless, and, for my money, one of the finest panaromas of Snowdonia there is.
Definitely worth the effort, although it's fairly steep it's easy terrain and it's not that far to walk if you're used to walking as you are (obviously it's probably quite a day trip from Swindon, although I did manage a day trip from Cheltenham, so you never know). If you go a little further up (say, Cadair Bronwen), the views on a clear day are unbelievable. All the main Snowdon ranges are visible in a continuous panorama.