Thanks John,
It almost certainly is an LU cash fare, though quite why that is available from National Rail outlets is beyond me. I don’t think it’s anything to do with Crossrail because the fare from Farringdon to the rail stations at Heathrow will be the same as, or more than, it currently is from Paddington. And the Crossrail fares which were added to the database in 2018 are all still there.
It will be interesting to see if it’s still there later today as it’s the third fare change day of 2021.
