Clear as Mud I reckon
The requirements are simple, and quite straightforward to replace or adjust, without the need of a mechanic.
HEADLIGHTS & TAIL LIGHTS must be free of chips or cracks; the headlight must also work on main and dip beam, the main beam must shine directly ahead and the dip slightly lower and to the left.
INDICATOR LIGHTS must all flash at a steady rate and the warning lights function properly.
If a HAZARD WARNING SYSTEM is fitted, all 4 indicators must flash at a steady uniform rate.
Bikes must have a red REFLECTOR on the rear of the machine, either bolted on separately or as part of the tail light lens.
And in detail - it doesn't specifically say that a passing switch is required:
http://www.ukmot.com/bike/1-2.asp
1.2 Headlights
Information
This inspection applies to: all machines, except those which have neither front nor rear position lamps, or have such lamps permanently disconnected, painted over or masked that are
. only used during daylight hours, and
. not used at times of seriously reduced visibility
If this situation occurs the vehicle presenter should be issued with an advisory notice recording the above and it should also be recorded on the carbon copy of the VT20.
A motor bicycle first used before 1 January 1931 does not need a headlamp.
A motor bicycle is only required to have a dipped-beam headlamp (but may also have a main beam) if it:
. was first used on or after 1st May 1995 and cannot exceed 30 mph / 50 kph with an engine capacity not exceeding 50cc. or
. was first used before 1 January 1972 and with an engine capacity of less than
50cc.
. any machine having a maximum speed not exceeding 50km/h/30mph
Method of Inspection
1. Check the headlamp emits a WHITE or YELLOW light
2. Check that the illumination of the
headlamp is not affected by the operation of any other lamp or the horn and does not flicker when tapped (see information column).
3. Check the condition and security of the headlamp.
Reason for rejection
1. The headlamp does not emit a light which is substantially WHITE or YELLOW in colour
2.
a. does not have at least one headlamp which illuminates when selected on:
(i) dipped beam
(ii) main beam
b. operation of the dip switch does not
(i) extinguish all main beam
headlamps and leave on at least one dipped beam headlamp, or
(ii) deflect the main beam/s to make them dipped beam/s.
c. either beam as selected is affected by the operation of another lamp or the horn, or which flickers when tapped lightly by hand (See info column)
3.
a. a headlamp missing or so damaged or deteriorated that its function is impaired. (See info column)
b, an insecure headlamp.
Twin headlamp systems
Information
On twin headlamp systems only one or both headlamp may be illuminated for either dipped or main beam. Each headlamp that can be illuminated on dipped beam must meet the requirement for dipped beam headlamps. Twin headlamps must be mounted either one above the other or symmetrically without regard to any side car and not more than 200mm apart measured from the edge of the reflecting surface. The tester should advise if both headlights should illuminate for either function and only one does so.
On machines without a battery or wtth an insufficiently charged battery, it willbe necessary to run the engine.
Method of Inspection
4. Check the condition operation and security of the switch.
Reason for rejection
4. A faulty or insecure switch.
! Worse part is I may have to pay for another test because straight after the test I went on holiday and couldn't book a retest till Thursday next week, thats either 10 working days after the test or 12 depending on wether Saturdays are considered working days as the shop is open then. Bit gutted really as this is the first time in four years it has failed an MOT and on such a crappy small thing too 
!