Yes - however what I didn't do was check the alignment between the two sides of the crank case. Thus I'm wondering if they're slightly out.

The problem is actually worse since I took the breather off and put it back on. Could the old gasket have moulded to the shame of the top of the crank case shape? if I then put it back in a different way, the profile ofthe gasket would be wrong causing the leak to be worse.

I'm going to make a new gasket today and see if that works.

The reason it's worse is more likely to be that you reused a gasket that's already become damaged by a leak. The crankcase halves can't be 'out' or have moved or anything, think about what else the crankcase does. Start with a new gasket, recut the thread with an m8 tap and don't be tempted to overtighten it.

It is conceivable though that someone warped the flange on the oil filler.

I will check again, but using the straight edge it seemed ok. I think re using the old gasket was a mistake.

Well, I think we're there. I made a new gasket and used some gasket sealant and there's no oil pouring out. Drove up to the barn this evening and there was some splattering across the bulkhead. I'm hoping this is left overs from yesterday. This seems feasible as it was pouring out yesterday morning. It's also clean oil splattering which would support this theory as I'd just topped it up before it came pouring out. Maybe I'm just trying to convince myself. I just want it to stop leaking!!!!

Fingers crossed, Sam.

Do you think the car actually needs to be moving forwards before the oil is flung on to the bulkhead, or is the oil just being thrown and blown around by the fan/pulleys/flywheel or whatever?

I'd have thought that it would be easy to see if it's a leak at the bottom of the oil filler - I'm sure you've cleaned around the flange when you re-did the gasket and any new oil wetness in that area would, I'd have thought, be quite obvious?

If there's still a slight leak issue you can't trace, perhaps you can tape A5-ish pieces of white paper in different places around the bulkhead and on hoses, etc. (not quite sure where ) and see if this gives an idea of where the oil is coming from after a run - ie: which ones have oil droplets on them. Any with oil can then have fresh paper attached further forwards and sideways of these points to try and isolate the source. (I just know that when I go out to the garage and have a look at my engine bay, I'll find that suggestion completely unworkable... )