I recently discovered that if you search fare between Farringdon and Heathrow Rail (HXX) on nationalrail.co.uk, and select train operator as TfL Rail only, you get £6 single fare. I thought this might be Crossrail fare put in place in advance.
But if you change from Farringdon to Liverpool St or Tottenham Court Road, the fare jumps significantly – which suggests Crossrail fare isn’t put in place at those two stations.
To put the matter in perspective, Oyster/contactless single fare between zone 1 and Heathrow Rail is £10.4 at the moment.
Did TfL allow Crossrail fare at Farringdon, but not other future Crossrail stations?