Yes I've heard two schools of thought about whether or not you should stop for a pedestrian which has not yet stepped off the pavement onto a zebra crossing. I tend to use common sense: if a person is walking towards a crossing and looks as if they intend to use it, I calculate whether they will have reached it before me, and I plan to stop in that case. If they are walking purposefully but I am *certain* that they will not have reached it before me, I keep going. If they are stopped at the kerb, facing to cross, I will stop, irrespective of whether it is a legal requirement in that boundary case: it takes a lot of nerve to step out into traffic on the assumption that it will be able to stop in time. Obviously you need to apply common sense: someone who is facing away from the traffic, having just crossed, is unlikely to turn round and cross back (though I won't say "never"). Two people who are having a conversation at a crossing and continue to do so after I've stopped for them clearly have no intention of crossing *at that time* so I will try to establish eye contact, as if to say "are we both agreed that you're not going to cross and it's safe to let me continue?" There's also the rule somewhere that it is not permissible for pedestrians to keep crossing backwards and forwards as a way of stopping the traffic as a protest: the police can move them on under some form of "taking the piss" type of rule. I don't have a citation for that; I'll have to ask my nephew who's doing his training to be a PC.