Genhis
The JAR-FCL definition of a TMG is: A motor glider having a C of A issued and accepted by a JAA Member State having an integrally mounted, non retractable engine and a non retractible propellor. It shall be capable of taking off under its own power according to its flight manual.
Maybe the Vigilant doesn't have a C of A, but it is accepted by the UK, a JAA State, as a TMG.