After the Mk1 there were two minor evolutions of the design, both primarily training vehicles though the Mk2 did see one battle. The Mk4 is the next evolution of this and was basically an up-armoured version of the Mk1 with some safety adjustments, such as an external fuel tank and a narrower chassis to allow for rail transportation.
This is one of 7 surviving Mk4s left in the world (our of 1220!) and only one of two Male variants left. I think it truly does deserve it's designation Excellent. Very Bill & Ted!
The Males were equipped with three machine guns and 2 6 pounder guns. The Females carried 5 machine guns.