This may sound to be a goofy question, but do you have an allergy issues? Some people can develop what is termed eosinophilic esophagitis (eosinophils are a type of white blood cell that can be elevated in people who have frequent allergic reactions, as well as people who have worm infestations, although I expect that wouldn't be too common in the UK). If people have chronic allergic reactions these eosinophils can cause chronic inflammation of the esophagus. I'd also recommend being checked for a hiatal hernia (hole in the diaphragm where the esophagus goes through is larger than normal, so the stomach starts to slide upward; it can cause heartburn and can be corrected surgically, often with keyhole surgery) if your provider has not already done so.