Devon General Society - 4 RDV (4) was one of eight AEC Reliance / Harrington Cavalier 41 seaters that entered service in 1964. Built to the special narrow width of 7 foot
Harrington Cavalier Coach, Southdown, 1-76 (Exclusive First Editions 12304) - The Brighton Toy and Model Index
IMCDb.org: 1963 AEC Reliance 2MU3RA Harrington Cavalier in "Carry on Abroad, 1972"