It’s against the law for a vehicle to overtake another vehicle whilst going through a section of zig zag lines right?
Wrong in the case of a motorist overtaking a cyclist. The Traffic Signs Regulations and General Directions 2002 section 28 states
a zig-zag line shall convey the requirement that, whilst any motor vehicle (in this regulation called “the approaching vehicle”) or any part of it is within the limits of a controlled area and is proceeding towards the signal-controlled crossing facility to which the controlled area relates, the driver of the vehicle shall not cause it or any part of it—
(a)to pass ahead of the foremost part of any other motor vehicle proceeding in the same direction; or
(b)to pass ahead of the foremost part of a vehicle which is stationary for the purpose of complying with the indication given by a traffic light signal for controlling vehicular traffic.
So whilst the Highway Code rule 191 only states
You MUST NOT overtake the moving vehicle nearest the crossing or the vehicle nearest the crossing which has stopped to give way to pedestrians.
The actual law only refers to motor vehicles. Motor vehicle drivers are allowed to pass non motor powered vehicles on zig zag lines and non motor powered vehicles are allowed to pass vehicles stopped on the zig zag lines.
We have to make sure we take extra care at zig zag crossings and if it is to safe for people to overtake us then we must take control of the lane to prevent them, as the law is not on our side in this case.