Not a whole Tank, but very impressive, and certainly gave me a surprise when I saw it this afternoon - the National Army Museum in Chelsea, west London, has a new small exhibition about technology in the world wars, and the entrance to it is a replica side unit to a Mk 1 or 2 Male Tank - it's just one side, with tracks as well, and Male Sponson, with a cut out behind the sponson to enter it, and looks very very realistic (wasn't till I touched it that I realised it was actually wood)
Unfortunately photography isn't allowed, but the Tank was painted dark earth (so I think that makes it more likely to be a Mk 2?) and was named 'Mars' - was this an actual Tank?