Heathrow Express have now withdrawn their 2nd tier of Advance Tickets priced at £22 sold between 30 and 14 days before travel.
In standard class (as regards single tickets) there are now only the £10 Advance Tickets (purchased up to 30 days before travel) and full priced £26 Tickets.
It isn't known when this happened, whether at the nationwide 1 September fares revision, or since.
There are also still the £30 day return tickets in standard class or £36 in 1st class.
This quiet change has come to light from a PM this morning, enquiring how to buy the £22 tickets.