The test is a bit flawed. If you make the bike wider by adding a reflector stick, then cars will have to give more adequate clearance when overtaking. So they need to allow an extra 1.5 metres to allow for the cyclist to make deviations for pot holes etc. So the refector stick needs to be 3 metres in length.
But wait, the car still has to give adequate clearance to pass the now 3 metre stick and again he should allow 1.5 metres, so to check that there is sufficient clearance, the stick needs extending by 1.5 metres, making it now 4.5 metres.
But wait .......
And of course there needs to be a similar measure stick on the left hand side to ensure that the cyclist gives sufficient clearance when over taking parked cars. This should also be xx.x metres