The vehicle was developed as a joint project between Optare and DAF; it was based on the designs of the successful MCW Metrobus which had been jointly purchased by DAF and Optare, but they are by no means a restlyed Metrobus. With the launch of the DB250LF chassis sometime after production commenced, the Spectra was built to low-floor specification, and was one of the first low-floor double-decker buses available in the United Kingdom. The design is notable for the exclusion of a lower deck rear window, a practice that has become more commonplace. The bus typically seated 47 on the upper deck and 28 on the lower deck in single-door format.