The requirement for licensing of aircraft maintenance engineers is contained in the Air Navigation (Overseas Territories) Order, principally Article 33.
The requirement to hold a licence is only applicable to those personnel working on an Overseas Territories registered aircraft outside the jurisdiction of an "Option 1" Overseas Territories Aviation Requirement (OTAR) 145 - Aircraft Maintenance Organisation Approval.
Requirements for aircraft maintenance engineer personnel licensing can be found in OTAR 66 - Aircraft Maintenance Personnel Licensing.
Although a formal medical examination is not required, there are requirements for general levels of medical fitness.
The issue of an OTAR 66 personnel licence is dependent on the applicant holding an aircraft maintenance engineer licence issued by another International Civil Aviation Organisation Contracting State. Requirements for the validation of a Maintenance Engineer's licence issued by another ICAO contracting state can also be found in OTAR Part 66.