Actually the UK CAA is authorised to use a great deal of discretion in the way it conducts its day to day activities as the UK national aviation regulatory authority. It also exceeds its authorised discretion on a regular basis where it deems it needs to. This can either work in your favour, or to your detriment.
To illustrate the point about the CAA's organisational disdain for all qualifications foreign, there was never even a proposal to allow the painless conversion of flight crew licences to UK licences under UK national licencing arrangements. The procedure was to obtain a "licence validation" which would allow the holder of a foreign professional flight crew license to fly G registered aircraft using their foreign licence.
Unfortunately BALPA managed to lobby the CAA to put an effective end to that. It seems that BALPA - who are no doubt just representing the employment aspirations of their membership - would rather have a 200 hour wannabee BALPA member flying around in a B757 than a foreigner with command experience on type. In capitulating to BALPAs lobbying, I suggest that the UK CAA has in one sense become an instrument of protectionist employment policy rather than a regulator of aviation safety.
Under JAR the mutual and painless licence conversion issue is at least on the agenda. Unfortunately it is being used by the European politicians and their bureaucratic empire-builders (including those in the UK) as an aviation regulatory power play against the United States.
Air transport is a global industry - why is it still regulated under the well and truly outdated Chicago principles? Isn’t it time we moved on?