I have just looked at the filter sets on Paddocks websites for my Disco 2 TD5 and noticed it includes a rotor filter. This may sound a stupid question and I am prepared to be "widculled by a wabble of wowdy webbles" but whats a Rotor Filter?

the rotor filter is a centrifuge that the oil passes though, it spins out tiny particle debris out of the oil.
it looks like a silver bowl, you will find it close to the oil filter by the turbo on TD5 engines only.

replace it every other oil change to keep your motor in top nick!