If that Panther G is from Bovington, then it could have been in just red oxide as the British Army had six Panther G's completed that were on the production line at M.A.N. for evaluation along with a few Jagdpanters as well. The Panther G in that photo if it is the Bovington Panther G has had at least three paint makeovers since that photo was taken. I have attached examples including the latest which looks close to your '60's photo. The one with the dark yellow strips over red oxide is supposedly what the original colors were from the factory where they were completed for the British Army?

Now the question is was this a Panther G from Aberdeen? Aberdeen Proving Grounds had several Panther G's as well. Many of them were scrapped during a scrap drive for the Koren War, amazing waste of history, but they were built as evaluation machines as well?

Or, maybe the Fort Knox/Patton Museum Panther G?