Claim: United Kingdom aircraft test serials are used to externally identify aircraft flown within the United Kingdom without a full Certificate of Airworthiness  and is a permit for commercial passenger or cargo operation.
Evidence: United Kingdom aircraft test serials are used to externally identify aircraft flown within the United Kingdom without a full Certificate of Airworthiness. A standard certificate of airworthiness is a permit for commercial passenger or cargo operation, issued for an aircraft by the national aviation authority in the state/nation in which the aircraft is registered.