A fairly unannounced benefit of being a Star Alliance Gold card hold or a member of British Airways Gold Guest List is a free upgrade on the incredibly expensive Heathrow Express from the airport to London Paddington (or return).
The train, which is supposed to operate every 15 minutes, takes about 15 minutes to Terminal 1/2/3.
To secure the upgrade you buy a normally priced ticket and show your membership card to the conductor on the train. There are reports that BA Gold Card holders have managed to secure upgrades but this is not the norm. Other passengers report that they have been told to move to Standard Class if they are not GGL.
The seats in First are very comfy with lots of space, and the carriage is typically empty. There is plenty of room for luggage and as the carriages are typically at the front of the train, you can be off in to the stations pretty quickly.
There are free newspapers in the carriage and free WiFi. Each seat has a power socket.