Well guys, as reported I went out and pulled the air cleaner (which I had replaced about 2 weeks before the 'incident') and it was as clean as the preverbial whistle...damn. When running, the breathers certainly produce vapour but not beyond what I would expect..back to the drawing board. Strangely enough I took her out for a short spin this evening as the smoke didn't look as bad...yeah I checked the oil level again - all ok. Guess what...no smoke, or certainly so little that I couldn't see it out the rear view, it has been windy though. I was too chicken to really rev very hard so maybe this was just because the car wasn't really trying (50mph tops).

It also occured to me that I hadn't carried out the 'sludge in the oil filler cap' test when the engine was cold so I'm going to do that in the morning. I really need to pursue this till the end as it's making me very wary of driving the old girl too much lest I do serious damage.