Sorry if the title is a bit opaque. If you will be in the UK in November or December, and are a couple traveling together with a Two Together Railcard, I have an unused Heathrow Express ticket for two people ( one way in either direction) that I would be happy to pass on, free of cost. I booked this in advance but we ended up spending our last night in Henley-on-Thames instead of London, and used the Heathrow Connect instead to reach the airport.
The ticket is freely transferable but must be used within three months of September 30. Send me a private message if you would like to have it. Just remember that this can ONLY be used in conjunction with a Two Together Railcard, with accompanying restrictions---such as not before 9:30 am weekdays.