My understanding is:
(a) Eurailpasses are NOT valid on Heathrow Express
(b) as almost always with local suburban rail operators, Eurailpasses are similarly NOT valid on London Underground (‘Tube’) trains (and buses/trams)
© Eurailpasses ARE VALID on the newly opened Elizabeth Line (Transport for London) between say London Heathrow Airport terminals and Paddington, or elsewhere on the route (though once one tries to connect to the Tube, one would have to have a valid Oyster Pass issued by TfL.
(d) Similarly, Eurailpasses “may” be valid on London Overground trains.
Is the latter - c and d- correct?
If so, where can one have a Paper Eurailpass validated at Heathrow? Will a TfL staffed booking office do it?
Best answer by Al_GView original