The warning message *** This registration has been SUSPENDED *** can appear in the WHOIS records of a .UK domain name where the domain has been suspended by the domain registry.
The .UK registry is very strict with enforcing their rules regarding the accuracy of contact data for each and every .UK domain name.
The registry would typically contact the domain registrant directly via email to verify the authenticity of the WHOIS contact details where their systems have automatically flagged a .UK domain for WHOIS inaccuracies. They would proceed with disabling the domain name where there is no response from the domain registrant.
Where the domain has already been suspended, this can still be remedied by the domain registrant who can review the emails from the registry and take corrective action.