I don't think anyone has mentioned this so far, and I'm kicking myself for not having realised sooner, but the MCW Metroliner is in with a shout here.
There was a total of 21 of the original single-deck examples built:
They were spread across five operators, three of which had "East" in their names! (East Kent, Eastern Scottish (Scottish Omnibuses), Eastern National)
There were only 21 single-deck (Hi-Liner) versions built:
Finally, while there were 154 normal double-deck Metroliners built, the 400GT model, designed to fit within the 4m height limit, numbered only 3:
Thanks to victoryguy.smugmug.com for the rabbit hole that I've been down for the last two hours!
There was a total of 21 of the original single-deck examples built:
Bus Lists on the Web
www.buslistsontheweb.co.uk
They were spread across five operators, three of which had "East" in their names! (East Kent, Eastern Scottish (Scottish Omnibuses), Eastern National)
There were only 21 single-deck (Hi-Liner) versions built:
Bus Lists on the Web
www.buslistsontheweb.co.uk
Finally, while there were 154 normal double-deck Metroliners built, the 400GT model, designed to fit within the 4m height limit, numbered only 3:
Bus Lists on the Web
www.buslistsontheweb.co.uk
Thanks to victoryguy.smugmug.com for the rabbit hole that I've been down for the last two hours!