The new API “Change Registered Office” Function is now active.
For clarification, this is specially targeted at Companies who have already advised their registered email address to Companies House and need to make a change to it.
This is REST API based, and the details (as well as a test sandbox facility), can be found here:
Manipulate Company Data (API Filing): (company-information.service.gov.uk)
Manipulate Company Data (API Filing): Registered email address (company-information.service.gov.uk)
SDN