Issues like this are normally where the individual has multiple accounts with the same email provider, with only small differences between them. Is the name that appears used in one of the other accounts?

Thanks, David ... but, no - it's not a similar name. But I kept searching and realised that the old Your Name had been put into the address folders with that email address. I just deleted that, checked that I had the correct name in the address folder with that address, and all is fixed. Seems that the system was using that name from the address folder rather than the name I had put into the account details. Anyway, I'll close the question now. Colin