I came across this press release from the consumer magazine Which?.
It's an investigation of commercial testing for food intolerance and allergy. It makes some good points. Probably the best point to note is that often problems are only identified through careful detection and keeping a record of what you eat.
However they undermine their case by stating that their researchers went to "hospitals" and managed to have one peanut allergy and one lactose intolerance diagnosed. I wonder if they filled in food diaries. Were they NHS hospitals or private one, I wonder, and how did they manage to jump the queues?
Of course there is no test for salicylate hypersensitivity. When I went to the hospital all my laboratory tests came back negative, even though I had classic allergy symptoms. When that happened, the consultant looked at all the foods I had told him, beer, tomato, pasta meals, avocado and suggested salicylate. I excluded salicylate foods and got better - but not totally better. He seems to have been right.