Until 31 May 2015, Star Alliance Gold members can benefit from a free and very easy Heathrow Express upgrade from Standard Class to Business First Class.
To benefit from the upgrade, you simply need to buy a full fare Standard Class ticket and be in possession of your Star Alliance Gold card. You then just take a seat in Business First Class on the train, and show your Standard Class ticket, and Star Alliance Gold card, to the ticket inspector.
Given that it is entirely possible that the ticket inspector will not know about this offer, I strongly recommend you also take a print out of the offer page.
Note that the upgraded ticket needs to be full fare, so if you benefit from a Heathrow Express discount code, you will not be able to combine it with this free upgrade.
For a full list of Heathrow Express discount codes, have a look at our recent post detailing all the current offers available.