I rang Wandsworth Council this morning to check this out.
Basically there is no such thing as a 'catchment' area, because they're state schools they have to be seen to being fair to everyone - they're very adamant about this. So places are awarded in the following order: 1. siblings and 2. distance from school. Both schools offer 90 places.
So, in 2008, all those with siblings at the schools got in (for admission in Sept 2008). Then they kept offering places in order of proximity to the school until all the places were taken. In 2008 the furthest anyone lived from Belleville who got in was 500m (half a mile) and for Honeywell it was 455m.
They don't yet know how far the distance will go for this year - because it all depends on how many people apply with siblings at the school. Once those places are gone, the remaining places are awarded in order of proximity to the school. Obviously though the closer you live to the school, the better your chances of getting a place. Hope that helps!
