Today, I rode the Pronto bus route from Nottingham to Chesterfield. The Pronto service is operated by Trentbarton and another bus company, Stagecoach, and it usually runs between Nottingham and Mansfield but every half hour on weekdays and Saturdays, it continues to Chesterfield in Derbyshire. The journey lasts for about 1 hour and 40 minutes and in both directions the bus stops for several minutes at Mansfield's bus station.
The Pronto buses are pink and purple, and are Trentbarton in their outward design; here is the one that carried me to Chesterfield:
previously mentioned Chesterfield in one of my posts about visiting Chatsworth House.