Quite unintentionally, you hit on a key issue. BA mostly operates in a closed market. If you doubt this, start your own - or get hired by - a lcc and try to take away one of BA's gate slots at Heathrow so that you can compete from a metropolitan hub airport instead of Luton.

Even more distressing is that BA is allowed to own the main airports in the UK (including LHR, LGW and STN in London, EDI, and GLA). Is this monopoly somehow better or different than when the government controlled it?

While we can argue about how profitable BA would be if they actually had to compete on an equal basis, it's pretty safe to assume that their financial position would be significantly eroded should they face level competition.