The Motor Vehicles (Wearing of Seat Belts) Regulations 1993

8.  A child restraint shall be regarded as provided for a seat for the purposes of this Schedule if—E+W+S

(a)it is fixed in such a position that it can be worn by an occupier of that seat, or

(b)it is elsewhere in or on the vehicle but—

(i)it could readily be fixed in such a position without the aid of tools, and

(ii)it is not being worn by a child for whom it is appropriate and who is occupying another seat.