A bayonet electrical connector has a spring loaded safety pin for locking the bayonet coupling. The pin projects into a recess, and a sleeve surrounds the part having the recess. The sleeve has a tab which projects into the recess, the sleeve being slidable to make the tab depress the pin against the spring bias of the pin, thereby to enable subsequent disconnection of the bayonet coupling. This design maintains a locking mechanism to prevent accidental decoupling of the bayonet connection, but makes the decoupling process simpler, by using, sliding of the sleeve and twisting to release the bayonet coupling.