In June 1983, Duple was sold to the Hestair Group, which had already acquired the long established business of Dennis Brothers of Guildford. Duple was renamed Hestair Duple and the Laser and Caribbean were given a facelift to try to improve their popularity. In 1985, a new coach model, known as the 300-series, was introduced. A bus version of the 300 was introduced in 1987, replacing the successful Dominant bus that had continued in production after the coach version had been replaced. A new integral coach of exciting design, with Dennis running units, was added soon after. Known as the Duple 425 (its coefficient of drag), it was greeted with enthusiasm, but the close tie-in with Dennis as chassis maker made dealers of other chassis manufacturers reluctant to use Duple coachwork. The business continued to struggle, but the deregulation of bus services, in 1986, caused uncertainty amongst bus operators and, as a result, little investment in new vehicles was made. By 1988, Duple's output was just 250 bodies. However, at the October 1988 Motor Show, Dennis introduced the Dennis Dart, a midibus chassis that would go on to be one of Britain's most successful buses. Duple displayed a bus body for the chassis, the Dartline, that was based on the 300-series but with a distinctive front design, featuring a stepped windscreen and curved lower panel.