maf writes
How difficult would it be to achieve a Heathrow-Croydon-Gatwick rail
connection ? It would reduce M25 load,*wouldn't it ?

I believe that all it needs is a small section of track to link the GWML
to the WLL to enable through running.

This would mean that trains from Heathrow would follow the existing
route towards Paddington as far as the Eurostar train depot. A link to
the Willesden-Clapham Junction would then allow trains to follow the
route taken by the existing Willesden Junction-Clapham Junction &
Watford-Brighton via Gatwick trains.

Problem then would be fitting them in amongst all the existing services,
which won't be easy.

--
Dave