I think it is a matter for individuals to decide but we certainly really appreciate our sons being local and having fairly local friends. Travelling times can really be quite long across our patch of South London.
Sutton Grammar does get a few boys from the Kingston area as the 213 bus provides a really good service-not that many from the middle of Kingston, but plenty along the route-you never really know whether they come to Sutton as first choice or because they didn't make Tiffin. I think to get to Wallington or Wilsons it would be a whole different matter and starts to feel very difficult.
We would have considered any of the 3 Sutton schools but personally felt the journey to Kingston would have been too much so never even looked into Tiffin (hence can never advise on it
To some extent it depends what your alternatives are and how you feel your child would manage with travelling and how far you have to go from the bus stop. I am always so glad when the evenings get light again and they are not coming home in the dark.