2. In this Part “animal” means a four—footed mammal capable of carrying the rabies virus, except one which—
(a)is lawfully being transported through the tunnel system, or
(b)enters the tunnel system for purposes connected with law enforcement or security and is under the control of a person approved in writing by the appropriate Minister,
and “tunnel”, except in the expression “tunnel system”, means a tunnel mentioned in section 1(7)(a) of the Channel Tunnel Act 1987.