Anyway, she was oven cleaning this week, and I fiddled around ('helping'), and realised the top oven does work - it is just the fan that does not work. The element is fine, and seems to go on and off, or at least the indicator light does.
Point is, is there any reason not to use it just because the fan has failed? Presumably using it with 'non fan oven' times and temps would be OK?
Why the fan doesn't work, I haven't a clue. It spins by hand OK, so is not seized. Getting to it seems to involve dismantling the whole lot, and I'm not about to risk a major cock up in the cooker department in the run up to Christmas.