What type of ticket did you purchase? The ticket type will be shown on your booking confirmation.

If you have booked an 'Airport Advance' then this is valid for up to three hours after your booked train in the event that your flight is late. You must have allowed at least one hour after the scheduled arrival time and you must get your ticket endorsed at the ticket office before boarding the train.

https://www.tpexpress.co.uk/special-...hester-airport