Just clicked through to :

http://www.bmibaby.com/bmibaby/en/cblogin.aspx

and saw:

tiny fares on bmi
tiny fares are a fare class on bmi and are not included in this offer.

Looks like its bmibaby OPERATED flights with a WW designator that are available for he offer - shame but they'd have to pay ME £5000 a flight to get me on ofe of those aircraft