There are at least a dozen at my base airfield alone.

Standardisation has never been a forte of the UK CAA. The now defunct CAA team of staff examiners, primarily concerned with commercial pilot testing standards, never in its time ever produced a standards document. They were an exemplar of: put ten people in a room and you will achieve as many opinions. GA standards were lead by the AOPA Panel of Examiners, another dispirit group but made up of a wonderful group of very experienced and knowledgeable characters. Each had their territories and they ran it their way.

Standardisation is now the all with knowledge and experience taking second place. A few hundred hours and a course of a few days and hey ho your now an examiner having past a rigidly standardised assessment. As many have complained here the examiner list is without control, with examiners complaining that they rarely have 3 - 4 tests a year. This comment reflects a norm. The club committee/owner/Ops.Desk/instructor and even candidates are now setting the standards.