Okay
John
I've checked two of the plugs, fourth and then the second from distributor, both looked okay to both me and my friend, but I took photos anyway so that you can see for yourself:
[EDIT] Yay!, success, first piccies that I've posted in a thread!
Didn't get around to checking the air flow meter, and neither of us have any carb cleaner anyway, but it's on the shopping list and we're going to Maplin's tm (Halfords is next door!). [Thinking] That said, it might be best to get the Cat checked out first.

Yep, that would seem to make more sense, right?