The Dartline was unveiled by Duple at the 1988 British International Motor Show in Birmingham, along with the Dennis Dart chassis. Initially offered in just one length, 9 metres, its most distinctive feature was its curved, asymmetric windscreen covering the destination sign with an arched top. Four pre-production vehicles were built at Duple's Blackpool factory in 1989, and were used as demonstrators. Of these, three were 9 metres long, while the fourth was for London Buses Limited and measured 8.5 metres. Production commenced at the end of 1989, with 27 8.5-metre versions for the London United subsidiary of London Buses Limited, and 34 9-metre versions. Of the latter, 14 were for another London bus operator, R&I Tours, while five were for Southampton Citybus, three were for Great Yarmouth Transport, another three were for Rossendale Transport, and two were demonstrators for Hong Kong. With the closure of Duple, the Dartline design rights were sold to Carlyle Works, and many of these 61 buses were completed by the Birmingham manufacturer and badged accordingly, although they retained their Duple body numbers.
Carlyle
A further 199 Dartlines were built in Birmingham between the middle of 1990 and the beginning of 1992, of which 140 were 8.5 metres, 16 were 9 metres, and 43 were to a longer length, 9.8 metres. All the 8.5-metre versions were for London Buses Limited, going to its London United, Metroline, Selkent and South London subsidiaries. Of the 9-metre versions, 13 went to Warrington Borough Transport and one each to Southampton Citybus, Isle of Man Transport, and Yeomans Canyon Travel of Hereford. Of the 22 C27-coded 9.8-metre versions, eight were ordered by London Country North West and delivered after that company's takeover by Luton & District, while the remaining 14 went to numerous small operators. Finally, all but one of the 21 C28-coded 9.8-metre versions went to China Motor Bus in Hong Kong.
Marshall
Carlyle closed in early 1992, and the rights to all of its designs, including the Dartline, passed to Marshall Bus. The Cambridge manufacturer built a final five Dartlines, all to the 9.8-metre length and coded C27, in late 1992 and early 1993, of which two went to Mayne Coaches of Manchester and one to Epsom Coaches. Total Dartline production was thus 269, including the four pre-production vehicles of 1989. In late 1993, Marshall redesigned the Dartline as the C37, with a symmetrical windscreen and a more substantial front bumper.
