The staff at Manchester security are consistently the rudest I've experienced across a lot of flying, including a lot in the USA. As has been said above, the fast track line is allowed to queue back substantially "to allow the regular queue to move", and the staff doing secondary seemingly just do whichever customer shouts loudest first, regardless of order.
After 2 (separate) horrific experiences being yelled at and belittled by their staff last year, I've vowed never to fly from Manchester again.