Hi Simon,
Thank you for responding and offering to help!
We had the site hosted completely on subdomain, then changed it to the primary domain but this 1 account-activation page is still on the subdomain. Everything else is on the primary (correct) domain.
I manually changed the email to not reference the {baseurl} with our domain as i couldn’t figure out how to change the baseurl variable - which appears is the same problem here.
Hope that makes sense?