Heathrow Express has extended the ‘free First Class upgrade’ promotion for British Airways Executive Club members until the end of September. It was meant to finish at the end of August.
Whilst you need to book by 30th September, you can use the tickets for three months from the date of purchase. This effectively takes you up to the end of the year.
This offer is ONLY available if you book via the dedicated Heathrow Express / British Airways website. The good news is that you will also receive a handful of Avios points with your purchase.
The discount only shows if you click through from ba.com. You need to visit this page on ba.com and then click the link to go to the Heathrow Express site.
The (minor) downside is that the upgrade is not genuinely free. You can currently save 12% on a Heathrow Express ticket by using the special Mastercard offer I outlined here.
This means that the upgrade is costing you the 12% differential in ticket price between the BA site and the Mastercard site, albeit this is offset by the 100 Avios earned.