Well, that bump to the 'New Welham Green Web Site' thread sent me browsing the local transport images linked therefrom.
I was pleased to see a couple of photos of one of Greanleaf's chubby little coaches, remembered fondly from the '60s.
(Slightly) more recently, I caught John Wyndham's 'Village of The Damned' on TV. I was convinced that one of these coaches featured in a blink-or-you'll-miss-it scene, lodged in a roadside ditch, presumably after the driver had vexed one of the little darlings on board.
Can anyone confirm my suspicion?