Thanks, much appreciated.
Firstly, children under certain weights, heights, ages, cannot be carried in unbelted non-travel seats, regardless of vehicle age - full stop.
Children under 3 years cannot travel in vehicles without seat belts. However, children 3 years and older (e.g. my grandkids) may be carried in the rear seats of a vehicle that does not have seat belts. So a motorhome first registered when seat belts were not compulsory and to which belts have not be retro-fitted may be used to carry children over 3 years old, but they must travel in the habitation area. (
Link) In other motohomes, it seems that older children must travel in rear seats fitted with belts; which is what I want to do as it's their parents who would travel in unbelted, rear-facing seats.
The current legislation of 'you must travel in 'dedicated travel seats' came into effect October 1997. From this date, the V5c should quote the number of travel seats, but not for vehicles manufactured before this.
FWIW, the V5c for my 2001 motorhome does not show the number of seats, which I suspect might be due to its taxation class of "PHGV". I wonder whether the October 1997 date you mention aligns with changes in type approval requirements, and whether that applies to commercial vehicles (even if converted prior to first registration).
The driver has a responsibility to travel with a safely secured load, so although a vehicle may be manufactured prior to Oct 1997, you could still be prosecuted for carrying an unsafe load (the 'load' includes humans), should an issue or accident arise.
Agreed. However, I suspect it would be down to a court to determine whether the carriage of unbelted passengers was dangerous, and carrying passengers in rear-facing is significantly less dangerous than carrying them in front or side facing seats. So the legality of carrying such unbelted passengers is by no means certain and I haven't found a precedent either way.
I would think your issue is more likely to be weight, as carrying extra passengers, and their luggage and supplies may well take you over the GVW for the vehicle.
My van has a payload in excess of 700 kg, so I should be OK for weight provided I remove one of the two leisure batteries, travel with little water in the tank, and am careful of how much kit we take. 4 adults plus 2 small kids weigh about 400 kg, leaving about 300 kg for food, drink, clothes, etc. That said, I'll still take the van over to a weighbridge as part of my start of season service because all vehicles seem to gain weight with age!
Thanks again, Geoff