If I were to.....................

[Grahamm]

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.
Laws ZPPPCRGD regs 18, 20 & 24, RTRA sect 25(5) & TSRGD regs 10, 27 & 28

Interestingly, the definition of "overtake" (see ZPPCRGD section 24) is when your front wheel passes the line of the front wheels of the vehicle ahead.

Consequently, you just need to adjust the timing of your approach such that *their* front wheels cross the Stop Line (if a light-controlled crossing) or the dashes in front of a Zebra crossing first, then you can pass them legally