I also live in London and never specified underground or trains only for any of these cities. Buses also cheap and air conditioned.

Also 2-4 months at best out of the year is not a great argument for public transportation not being the better option compared to cars and parking that don’t scale.

Side note, Elizabeth, District, Circle, Hammersmith & city, and Metropolitan lines where many people work are air conditioned. So are the trains to paddington and St. Pancras from any “village” outside of the London zones. This summer especially it’s been good for me.