What sort of moped is it, then?
If it's a proper bike, the rules are clear:
Exemptions
For this test if a stop lamp is fitted, it must meet the requirements of this inspection, but need not be fitted to a machine which:
a. cannot exceed 25mph, or
b. was first used before 1 January I936.or
c. was first used before 1 April 1986 and which has an engine capacity of less than 50cc.
http://www.motuk.co.uk/mcmanual_130.htm
I can't believe that a tester would pass a proper bike which has no lights, as you quote. How would anyone behind you realise that you were braking?