Well the engine was still very hot when that spark plug came out. We only took one out as the car was in the queue for the start line! But it was the same plug that got pulled out at Eurotec and was completely black.
As for whether the cylinder was far too lean - possibly. At this point the engine as a whole wasn't too lean - it was later that I leaned it off.
Which brings me to this mornings updates... Took the car down to the local garage to check the mixture - CO was at 0.9. So my leaning off antics yesterday had gone too far. Reset it to 2.5, put on the air filter and suddenly it jumps to 3.5. Hmm! Checked the air filter and it was completely clogged. So put it back on and reset the mixture with the air filter on.
So that certainly won't have been helping up the strip on a hot and muggy day...
Next stage - try and clean the bugger out. Not convinced that simply replacing disposable ones isn't the way to go!