Topping up the oil on Sunday. Left the bonnet open with a funnel inside the oil filler hole while I went to put the oil back in the boot. Wind caught the bonnet and it came crashing down. Broke the plastic funnel. Two bits went down under the camshaft. Had to take the rocker cover off (turned out to have been stuck on to the gasket). The bigger piece of plastic came out easily enough. The smaller one was half way down the oilway and needed some encouragement to come out.
Duh!