135 Triumph 2000 Saloon (1963-69)

Some time ago i bought this playworn, but rare colour version of the 135 Triumph 2000 sedan. Can anybody provide some information about this one? It seems all original to me as it has it's factory rivit and the inside of the body has the same colour. Is this the promotional Cactus green version, but without the black roof? Maybe a factory error? Greetings, kasvd