The availability of suitably-qualified aircrew means nothing. Grounds for objection must involve the availability of an aircraft for those pilots to fly, controlled and operated by a UK/EU airline.
If there WAS a UK airline with B747-200F, -300F, or 400F capacity available to operate this service, then this airline would be objecting. Clearly there is not. If the CAA listened to your objections and denied an extension of this consent, the Atlas aircraft would simply be re-deployed to another contract somewhere else in the world.
With the greatest respect Basil, the CAA have no mandate whatsoever to "withold approval of this foreign charter to BA until all avenues leading to operation of a British registered B747employing British crews have been fully explored."
What are you suggesting they do; set up their own airline?
