misfire

Hi all,been out in the Derbyshire snow enjoying myself and all was fine V8 disco 2 running beautifully until engine man light came on and she started running rough.Then eng man light started flashing and I could hear a sort of knocking noise from the engine I think.
Got back home light still on and still with a misfire.
couldn't see anything wrong in eng bay,smelt really hot though and definitely not running on all 8.
Just wondering if you've any ideas?
Thanks in advance.

blocked rad causing it to oveheat? wet plug leads?

Cheers for quick reply. No overheating on any gauges just smelt hot when i opened bonnet and all looked dry around plugs/leads.

Found problem thanks,HT lead broken inside the cap so not sitting on plug nipple tightly.