At the moment mainline pilots fly ad hoc for baby on an 'as req'd' basis.However over the next few weeks Midland pilots from all fleets are being asked to bid to join baby as a separate company, on new T&C's. These conditions have been published as proposals to be discussed & agreed by CC.
Positions are only available on B737 at EMA & CWL. Once the bidding process is over, then the company will assign fleet & base on seniority.
Thats the idea anyway, but I believe a lot of hot air will be expelled before it happens !!