Richard J. wrote:
In that case small windows will be very welcome in summer. Trains
running on the surface with large windows and no air-conditioning become
mobile greenhouses. The same goes for buses too.

Except TfL/the bus operators have no excuse for not putting air con on
buses. There's hardly the same 'it's too hard' argument you have with
the underground, just a matter of money - and air conditioning isn't
expensive these days anyway.

Jonathan