My guess on the Mk1, It was taken off something very early before it was worn out and kept in a box 'till now.
Reminds me of a tale from Geoff Ballard about a Bing a bloke gave him when he ordered a Mikuni 'cause he was told the Bing was shit and he 'had ' to put a Mikky on it to make it go. Geoff took one look at it a had a smile- :Dok, sure he says. The Bing was almost brand new.