BA are offering their Exec Club members a discount of 25% off Club Europe flights from

Fly Club Europe (business class) from London Gatwick to Tirana or Pristina. From London Heathrow the offer is valid on flights to Warsaw, Prague, Sofia, Budapest, Bucharest, Kiev and St Petersburg.

Voucher “UK-EASTCE12”

Booking period:	10 February – 13 February 2012
Travel period:	10 February – 25 May 2012
Discount:	25%
Cabins:	Club Europe (business)

I tried this and it works fine. You can either use the link from this page https://www.britishairways.com/travel/eastern-europe/execclub/_gf/en_gb?source=home&openxzoneid=303&openxcampaign=cfseasterneurope&openxbanner=10795&openxtype=click

or you add the voucher code above when booking: