It's a modification so you have to tell your insurer and they may wish to inspect it. Side facing seats are dangerous in the event of an accident (and are illehal in new vehicles) so expect your insurance premiums to increase. The tax class should be changed from a light goods vehicle to a car and the V5 changed to reflect the increased number of seats so you should inform DVLA about the change.

Thank you for you help that is quite clear

European Legislation (EC Directive 2005/39/EC) states that to travel in a sideways facing seat with a seat belt is unsafe and that from 20th October 2007, new vehicles will not be allowed to be registered with sideways-facing designated travelling seats.

I think you can still have them but they have to be designated not for travelling and marked accordingly.

I believe that the new Land Rover County no longer has side facing seats.

No, only cars and light vans. I am almost certain up to 8 seats maximum capacity but don't quote me.

You can have side seats in a camper van but they should not be used for transportation and now have to be marked as such.

If they are used for transportation there is a potential charge if stopped of "carrying passengers at danger".

My neighbour has a LWB Land Rover County with rear side seats for thir shoot and was advised to remove them (by a specialist Land Rover insurer) or the premium would be extortionate.

I believe there are people who now specialise in supplying forward facing seats for this reason.