Apologies for lack of info - first 2 posts were done from mobile, so short and sweet.
Jimbob pretty much hit the nail on the head on the first page.
For those following the tractor saga will know that in an effort to to stop stripping sump plugs on this stupid bmw monkey metal engine, I fitted a 'quick drain' plug to it. M_DTM helicoiled it to fit. It hung slightly lower than anything else.
Nipped out to dealer yesterday morning, during an early lunchbreak. So many knobheads driving at stupidly low speeds made me late, so I decided to come back the back way, round the country lanes.
It was going well, until I hit a bump a tad quick, and having a boat anchor for an engine meant that the front came down a bit hard. This ripped the sump plug out.
I knew exactly what had happened (the noise of the sump plug rattling down under the chassis, and the black cloud in the mirror), so pulled it up quick (in a gravel layby as well

) and got it switched off before the oil light could come on. Looked for sump plug, couldn't find it.
Got Mrs TheBoy to tow me home, but had to leave on road (drive has a slope, no way could we push it up).
Not wanting it left on the road, I put a spark plug in the sump, put some oil in, and moved it under its own steam on to drive.
Went to Pug dealer to get some suitable sump plugs, which I fitted earlier today. Put yet another 6.5l of oil, and started her up. The tractor breaths again.
I shall take out for a spin tomorrow.