The stereotypical idea of PAT is simply plugging an item into a tester, pressing a button, waiting for a PASS or FAIL and putting a sticker on a plug. Even if this were true, it identifies that the only person to do a full PAT is someone with the relevant test equipment.
However, the name Portable Appliance Testing has changed, even though people generally are not aware, and it has been intentionally used in the title of this page and on our advertising material because people don't know that it has changed. The correct term now is "In-service Inspection and Testing of Electrical Equipment" because the emphasis is on Inspection.
That means that any 'competent person' can conduct the larger part of the task but does that 'competent person' know what they are looking for? For instance, what fuse rating should be fitted to a 13A plug? It depends on what equipment is on the other end of the cable. Do all 3-pin plugs need an earth? What is the maximum electrical load on an extension cable? Is that still true if it is coiled up? A person who is qualified by City and Guilds 2377 is the only person that you should trust to know the answers and to thoroughly inspect and test your appliances.