The Rover-Landers of BC

Recently acquired a 95 Range Rover Classic County with a 4.2L motor. It had been parked for @ 3 years, so new fuel pump went in & tank cleaned.
Was running nicely at the yard, but when I ran it 10 minutes to my house the passenger side cat was starting to glow red and noticed a tick tick that wasnt there before.
This is the first time that I have run into this happening, cam anyone shed some possible light on this or have any suggestions on where to start looking for issues? Have a new set of plugs on the way.

See:
https://www.linkedin.com/pulse/20140721 ... ow-red-hot

Thanks for the link, it confirmed what I had suspected ,and read, that it was unburnt fuel reaching the cat.
Now I am trying to narrow it down as to why the unburnt fuel is getting to the cat in the first place, I am changing out all the plugs this weekend, and will be putting some injector cleaner in the fuel. Is there much else I can do at this time to help things out?

An update, I pulled the plugs and swapped new ones in(7/8 of them, the front drivers side one I couldnt get my socket on to, seemed like the opening was a smaller diameter than the rest??).
Also ran a bottle of injector cleaner through.
Voila, no more hot cat and running much smoother.
Always happy when it is a simple fix. Phew.