@BEagle
As narrated in CAP 804:
4 Conduct of skill tests, proficiency checks and assessments
4.1 Before taking a skill test, applicants are advised to verify with their examiner that he holds a licence issued by the CAA, or has been briefed by the CAA. Under Part-FCL (FCL.1015(c)), any examiner intending to conduct a skill test, proficiency check or assessment of competence must have the same State of Licence Issue as the pilot who is to be tested, or he must notify the Competent Authority of the State of Licence issue of the pilot who is to be tested of his intent to conduct the test and obtain a
briefing from that Competent Authority.
Hence, the examiner must have the INSTRUCTOR CERTIFICATE.
WP