YOWkid,

Found a topic over on the BA board which asks a similar question for a BA flight. The general consensus is that there would be no refund.

http://www.flyertalk.com/forum/Forum15/HTML/002363.html

I'm sure you can afford an extra 4GBP anyway ;-) If you want compensation just ask for a double when the drinks service comes round.

Enjoy the flight.

Nick