Historically people in the Whitehall Park area have sent their children to a number of schools. These have included, (in no particular order) Yerbury, Hargrave Park, Brookfield, Coleridge, and of course, Ashmount. Then there are Church Schools St Michaels, Highgate, St Johns, Upper Holloway, (Both C of E) and St Josephs, Highgate Hill (Roman Catholic) there are also three private prep schools. The difficulty of getting into a particular school can fluctuate very much from year to year. These days Yerbury would be seen as too far away for reception entry as such, as would Brookfield.
This is the third year that Ashmount is over subscribed and so actually has a radius of admission. Before then despite being a "good" school and with excellent feed back from parents whose children attended the school was underscribed, with vacant places. It was when, after many years rather convoluted gestation, the decision to build a new building for the school, and thence move the school there was finally confirmed that the undersubscription stopped. I imagine this is due to a combination of the publicity associated with the new building, combined with the way parents were put off by the old building.
So things can change, and change quite suddenly. So far as Ashmount is concerned it would be useful to know how many places were filled by siblings. I say this partly because that fluctuates in all schools from year to year, partly that families moving into the general area, say during the school year with children for year three and above (this year) have been able to get places for their older child(ren) in Ashmount at once, and of course this has created a sibling entitlement.
In my view what really happens here over the next few years depends on how mobile people are. There are a LOT of young families in Crouch End. But if people do not move, their families will be complete, and in due course there will be lots of teenagers but it would not surprise me if in five years time - say - we are back to a situation were there is an over supply of places.