Apparently some clueless sysad (yes, there are some) has configured their email system to convince people that they have email addresses that they don’t really have.
So. If you think that you have an email address at the domain harrison.org.uk then you probably don’t. Similarly, if you are trying to contact someone @harrison.org.uk then, unless that’s their surname, you won’t.
It’s not my fault that you’re wrong, but because you’re wrong, I’m reading your email.
If you’re happy with that, then fine. Otherwise, sort it out.
And here’s the rub – there’s nothing I can do about it. I can’t tell what the email should be, I can only tell you what it isn’t.
It isn’t @harrison.org.uk