BA do not 'own' any of the slots or the routes that GB operate. All the slots are owned by GB under grandfather rights rules, although a few of the slots have been temporarily swopped with BA for mutual convenience; eg one GB slot at xxxx hrs swapped for a BA slot at xxxx hrs for a season to ease programming constraints. All routes within Europe are not 'owned' by anybody, and anybody can fly them, although GB cannot fly a route under the BA brand without BA giving permission, which presumably means BA cannot profitably fly it themselves. For the routes outside Europe that do require a licence from the respective countries national governments, GB holds the licence, not BA.
I know that BA pilots don't like it , but the fact is that BA(the company not the BA workforce) sold the right to use the BA brand on certain specific routes for a certain amount of time (until 2010). BA gets the money and GB flies in BA colours.
And, in 2010 BA will have to decide whether it wants a 20 aircraft airline to remain a friend or to become a competitor in its own right or possibly in partneship with one of BA's rivals.