I travelled from Chelmsford to Heathrow this week and enquired with the ticket office on the cheapest way to do this as I had planned to get to Travel Card singles - both off peak. I made it clear that I wanted a ticket that covered the Elizabeth Line from Liverpool Street to Heathrow. I was told that the open return (attached) was valid. On arrival at Heathrow, the station staff said the ticket was not valid and was for underground only. I know that when I purchase a travel card it says travel card zones and that the use of travel cards to Heathrow has been previously discussed. I sent a tweet to both Greater Anglia and TfL to understand who is right or wrong but neither have bothered to reply. When I look up code 1A. I can't see any restrictions covering the Elizabeth Line. Having landed yesterday evening, I got the Piccadilly Line back and it took over three hours to get home but this was more to do with the perils of late travel on a Friday night. I'd welcome any thoughts on this.