The OP is right. If there's an island it counts as two crossings. If the island is a small one though you need to be very sure the pedestrian knows Highway Code rule 195 as well. If the pedestrian is on the pavement and heading for the crossing you should be ready to stop.
Taxi driver tried to give me a bollocking last month for failing to stop for two peds on the kerb. I'd actually eyeballed them and seen they were chatting (and then heard, they were speaking French) and not even about to step out. He was still insistent I should have stopped.
I lose count of the people stood on the edge of the kerb looking like they're about to cross but they're chatting with someone or on the phone, or quite often just staring at the view. It's especially bad when they lurk right by a zebra crossing and you stop but they have no intention of crossing. gah!