The good news is that as soon as there is a tiny bit of warmth in the engine it slows to a steady drip, rather than the home-made tribute to the Manneken Pis that you see here.
I've not had the car up on a ramp yet, but as far as I can tell it is coming from the oil filter, from the side nearest to the block. It is a spin-on type and was recently changed during a service for another Moss one with the same part number. We had some trouble getting it to go on and I am after some thoughts as to why it is leaking the way it is. Current thoughts are a bad seal, a crossed-thread, a badly cut thread, or a damaged gasket between the housing and the block. I am also curious as to what part expands when it warms up and seals the gap?
Also can anyone confirm that the Halfords HOF203W is the same as the Moss GFE166. I know there are two different Moss adapters and that GFE166 is the one that was previously fitted to my car. The Halfords one looks to be a sturdier can, but the car I got the part number off also has an oil cooler fitted, which mine does not. The car goes on the ramp on Monday, so I can nip and buy another Moss one if there is a chance the Halfords one won't fit.
New Halfords filter has been bought and is ready to go on, but I am might have to do an emergency dash to Moss if it isn't the right one. For the price they are, I didn't even consider trying to reseat the one that it is on. I could just do with some assurance that the Halfords part is directly interchangeable with the Moss one. I will inspect the leaky one closely when it comes off, as I would like to know the cause of the leak.
Quick update. Had the car up on a ramp yesterday morning and it appears that the oil filter was simply not screwed on tight enough. The new filter was fitted a couple of months ago when the engine was still rather hot, and I think this prevented the filter from being screwed on fully. So in future an oil change will only be done in conjunction with other work, or at my local garage which is less than half a mile down the road. I have done one check after letting the car stand for 3 hours, and there was no sign of any leak. I'll check it again from a completely cold start, but I am optimistic that the problem is now resolved.
BTW the roads were wet yesterday morning and my car had left lovely rainbows for about a quarter of a mile down the road!