Your surviving Whippets are Bov's, Brussels, the ex-APG exhibit in the USA (Where ever that's gone to), Borden (Canada) & Pretoria.
All varying shades of green, apart from the Pretoria example.
Easiest one to paint, would be Pretoria's! allatsea.co.za/blog/wp-content/uploads/2014/04/whippet01.jpg">
Be different, why not model it as this preserved example?
Strange - the video done by David Fletcher shows the tank as a medium grey!!!!
The assertion that there were two Whippets came from (guess) Wikipedia, which showed two in different locations: my apologies for causing confusion.
The Brussels tank is a very dark green - has anybody got a Humbrol (or other paint make) equivalent?
The Pretoria Whippet is just plain silver - if one were to do it, I think you would need to do the whole set-up with the shells and the guns, together with the plaque on the front - it forms part of a designated war memorial. We have been trying for years to get it transferred to the National Museum of Military History, but no luck so far.