Instructions:Hi - my first post ;-)
Just found latest promotion code for 50% off Heathrow Express on tripadvisor.com
Code is: WP4518
Applies to single tickets only so if you want a return then buy 4 singles. I just bought 4 singles for our trip to Dublin tmrrw and saved £28.
Heathrow Express is the direct 15 min train link between Heathrow and Paddington Station - www.heathrowexpress.com
Hope it helps someone - now I'll have a smile on my face all day