SCOPE is an abberation to the modern-day world. Regardless of how you apportion overheads or anything else, I would challenge anyone to categorically state that BA's costbase is lower than that of GB or other franchises on a like-for-like basis.
There are some routes within BA which are absolute basket-cases and certainly were (not so long ago) losing so much money that they had no right to be in existence. Take Gatwick-Bilbao, for instance. Scope clauses dictate that there is no problem with BA dumping that poorly-performing route, but there is a problem with GB Airways taking it over if GB believes that it can make a profit on it. The provisions of scope mean that BA would prefer to dump a route and let a non-BA competitor take it over and make a profit on it rather than allowing a company close to home to do so, thereby still contributing franchise fees and connecting traffic revenues to BA coffers and maintaining a BA presence on the route.
BA and its unions are neither tackling the inherent problem of BA's costbase which means that it cannot make money on routes where others can; and its fall-back option is to yield routes to its competitors to make a profit out of it due to scope. How can this be in the interests of anyone other than BA's competitors?
And before anyone harps on at me about BA's costbase, just look at the industrial agreements over and above CAP371 within which BA crews (both flight and cabin) work. That, coupled to the bid system, has to cost money which is part of the problem.