One of our members recommended a guy called Gavin Seal. He seems to work in a couple of different practices in London now (I googled Gavin Seal endodontist), for example, here:
Dr Gavin Seal is a brilliant endodontist and has an extensive knowledge of everything relating to root canals. Gavin is a root canal expert with over 20 years’ experience of practice limited to endodontics. Following his first degree in Dental Surgery at Guy’s Dental Hospital, Gavin proceeded...
38devonshirestreet.co.uk
He used to work at this place:
For a range of dental treatments visit our private dentist in London, The Dental Surgery boast a friendly team who offer a variety of services.
www.thedentalsurgery.co.uk
That's where the original recommendation for Gavin Seal was for, but it looks as if they've got a new endodontist now called David Jones. He also sounds very good - having a background in community dentistry, he should be good at helping nervous patients. Again, he seems to work in several different places in the London region (as many specialists do). Unfortunately, the prices of some of those places are truly eye-watering, so it pays to compare different locations. Having said that, they might all be eye-watering!
Google reviews are quite good these days for feedback from other patients, though you'll have to search for the name of the practice rather than the individual practitioner, and then go through all the reviews in the hope of finding references to the dentist of your choice...
The London area is rather big - if you're happy to narrow down which part of London and how far you are happy to travel, maybe someone like
@drhirst might have some suggestions!