http://www.caa.co.uk/docs/1580/NPPL%...01%200%200.pdf
(14) On a flight to which this paragraph applies –
(a) there shall, subject to sub-paragraph (b), be
carried not less than one member of the cabin
crew for every 50 or fraction of 50 pa
ssenger seats installed in the aircraft;
(b) the number of members of the cabin crew
calculated in accordance
with sub-paragraph
(a) need not be carried if the CAA has grante
d written permission to the operator to carry
a lesser number on that flight and the opera
tor carries the number specified in that
permission and complies with any other terms and conditions subject to which such
permission is granted.