That isn't what the Highway Code says. Rule 191: You MUST NOT park on a crossing or in the area covered by the zig-zag lines. You MUST NOT overtake the moving vehicle nearest the crossing or the vehicle nearest the crossing which has stopped to give way to pedestrians.
Yeah I see what you mean.. the Code does word it like that. Thing is, the zig-zags themselves are classed as a full controlled zone under the regs(TSRGD), so technically no overtaking or filtering anywhere in them. Bit of a confusing one, I thought the same before too.
However the TSRGD says the same: the reference to a motor vehicle in paragraph (a) is, in a case where more than one motor vehicle is proceeding in the same direction as the approaching vehicle in a controlled area, a reference to the motor vehicle nearest to the signal-controlled crossing facility