Previously I mentioned the T34 in "Dress up" at the IWM Duxford, there was another two vehicles there that were not as they seemed.
Canada started licensed production of Sherman tanks (as the M4A5 Grizzly), based on the M4A1 pattern (cast hull and Continental Radial Engine), however from their experience with the Ram, there were some minor modifications: the armour was thicker (some examples) and sloped more and the track used was lighter and simpler and did not use scarce rubber. The track required a different 17 tooth drive sprocket (the M4 used a 13 tooth sprocket).
They built 188. As US production of the M4 series was thought to be sufficient, production was then turned over to the Sexton Mk 2.
After the Second World War a number of Grizzly tanks were sold to Portugal. They remained in service until the 'eighties. It is this late survival which has led to their appearance in museums, as the other marks of Sherman were either lost or scrapped.
So, if you see an M4A1 Sherman, it might be a Canadian in disguise.
So, going back to IWM Duxford, here are some pictures of the example that was there in November 2015.
The D-Day museum at Southsea (near Portsmouth) has an M4A5 outside.
Sherman Minutia page