As somebody unfamiliar with London but considering moving there, it would be great if instead of specifying a geographical radius for the search I could specify a commuting time radius with respect to the City. This would probably be useful even to natives, as I'm sure there are probably many areas where people overestimate commuting times and consequently avoid an area that otherwise should see greater housing demand (thereby levelling out demand and prices, in time, in other areas).

Of course I understand implementing something like this is quite complex, and you'd most likely have to precompute these things and limit it to a few common business centers as destinations, but it would be really preferable to my current strategy of "look for something that seems reasonably priced and then use another site to figure out if it falls within the 1hr commute window I'm looking for".