In the 1970s the great majority of coaches sold in the UK had comprised a British-built chassis with separately assembled bodywork by one of the two dominant domestic coachbuilders, Duple and Plaxton.

The other prototype employed Dutch BOVA running gear within a unique style of semi-integral body known as the Duple Calypso, and a further 50 production vehicles of this type were built for the 1984 season.

[1] The styling of the Calypso was a hybrid of the contemporary Duple Laser and Caribbean coach bodies which were produced in larger numbers.

[2] In June 1983 Duple had been sold to the Hestair Group, which had previously acquired the British chassis manufacturer Dennis Brothers of Guildford.

[3] As a result the contract with BOVA was not renewed after the 1984 season and instead the fully integral Duple 425 was developed as a replacement for the Calypso.