When it’s a Challenger of course!
My son and I visited The Tank Museum at Bovington in Dorset last Saturday, to go to Tankfest 2014. Among the many tanks that we saw was this one - a Challenger 1 Main Battle Tank, used by the British Army in the 1980s and 1990s.
Clearly someone has a sense of humour, as it bears the name Churchill - which was a totally different tank, from 40 years earlier!