Rule 19

Zebra crossings. Give traffic plenty of time to see you and to stop before you start to cross. Vehicles will need more time when the road is slippery. Wait until traffic has stopped from both directions or the road is clear before crossing. Remember that traffic does not have to stop until someone has moved onto the crossing. Drivers and riders should give way to pedestrians waiting to cross and MUST give way to pedestrians on a zebra crossing (see Rule H2). Keep looking both ways, and listening, in case a driver or rider has not seen you and attempts to overtake a vehicle that has stopped.

Rule 19: Zebra crossings have flashing beacons

A zebra crossing with a central island is two separate crossings (see Rule 20).

Law TSRGD Schedule 14 part 5