Many thanks for the prompt reply. Appreciate others offering help.
I had gone through the processes you mentioned but without success and was on the point of giving up until I had what seemed like a daft thought, at least until I tried it.
I reset everything as previously but this time before starting Domoticz from the cmd line I cleared my web browser cache. When I started Domoticz this time it opened without a password. I have repeated this a couple of times and it seems that clearing the browser cache is a required step, at least on Windows. I mention this in case others have the same problem.
So, on with the build, two sensors working with a bridge. Time to scale up :~)