Davidv - there have been many discussions on this forum about this....the law is actually quite straightforward.
The law permitted you to carry passengers in side facing seats without seatbelts for a period up to about 2009 when a further law
superceded this loophole which made it illegal to carry passengers in a vehicle without being in belted forwarded facing seats.
(Buses and trains have an exemption except for children).
Additionally another law is in place in relation to carrying unrestrained loads....so the bottom line is if you do it and
if you are caught you
face prosecution. In the event of an accident you may well be left with no
insurance cover should your passengers decide to seek damages,
and you will have to find the money for injuries yourself....bye bye life savings, and possibly your house.
You can look up these laws if you search for them....I can't quote the relevant legislation off the top of my head.
Effectively this means older Romahomes, and multi berth motorhomes with side seats are now effectively 2 berth while travelling and only
multi berth when stationary....which is why many are now up for sale....I was nearly caught myself when i was looking at a motorhome some
time ago......additionally many of the older motorhomes are not LEZ (low emmission zone) compliant...so you are screwed taking them into the London LEZ and many other zones which are cropping up frequently across the EEC.