Re: One cylinder won't fire...
First thing I'd do is swap plugs around - 5mins immediately tells you if the plug is sound and also the rest of the ignition system. If the replacement plug in No1 gets wet it sounds like you have an ignition problem. If the plug that was in No1 (and which you have in the meantime cleaned and heated on a gas ring or using Bunsen) works fine in another cylinder, then you had one problem and you've isolated it.
If No1 gets wet again and the thing runs (or tries to) on two cylinders you know you have two problems, and what they are.
Someone might have already mentioned a bad distributor cap. Try going out to it in the dark, opening the bonnet and firing it up, suprising how visible tracking can be.
Doesn't say that in the manual