Heathrow Express deals are continuing! They are currently offering a free upgrade to first class.
To benefit from this particular Heathrow Express deal, you have to book through this link. You will need to be a member of the British Airways Executive Club, but you can join that instantly, for free, here.
You’ll also earn 100 Avios for a single ticket and 200 Avios for a return ticket purchase.
Given that this offer cannot be used in conjunction with any other, it is worth comparing it to the discount options otherwise available to you. These are summarised in full here.
The free upgrade offer runs until 31 August 2014, and you can travel up to the end of November 2014.