There have been two serialisations of Enid Blyton's 'Famous Five' stories, as John Wakefield and I discovered while researching this entry!
The 1978/9 version modernised the stories; the 1996/7 remake put them back into the era in which they'd been written.
Five Go Down to the Sea (1978)
A travelling show arrives in Bedford OB/Duple JXT482. This 1948 bus converted to a caravan was new to the Metropolitan Police. It was still extant in 2008, albeit registered ESL175:
In the 1996 version the bus is replaced (disappointingly) by a horse and cart.
Five Go Off in a Caravan (1978)
Has footage of a Hants and Dorset Bristol LH/Eastern Coachworks, unfortunately not clear enough to identify in the footage I've seen.
Five Go Off in a Caravan (1996)
In the 1996 version, the bus is played by 1950 Bedford OB/Duple MHU52, new as Bristol 210, but now with Ron Greet of Broadhempton.