I'm not a fan of the way BA treats it's F passengers on the ground but your experience was probably a one off exception.
Our last F departure from LHR was actually pretty smooth - leisurely stroll from the lounges to the B gates short wait then priority boarding took place. Apart from a bit of a wait on the jetty till they sorted out a wheelchair passenger there was no real problem.
Even Lufthansa get it wrong. My last flight with them in J from FRA ended up with the boarding process being a total shambles due to staff cutbacks. One boarding pass checker for a well loaded 747 with no priority boarding.
