[1] In 1997, Epsom Buses expanded into the London Bus market initially winning the tenders for routes S1 and 413 which were operated with Optare MetroRiders later being replaced by Plaxton Pointer bodied Dennis Darts.

In 2003, Epsom Coaches rebranded its bus division as Quality Line and repainted its vehicles from their traditional cream and brown into all over red to comply with Transport for London contractual requirements.

From July 2006 with the introduction of routes E15 and E16, Quality Line began to return to operating outside London with buses in their traditional cream and brown livery, however since the displacement of Alexander bodied Dennis Darts from route S1, buses outside London have been appearing in red once again.

[1][4] On 12 October 2012, Quality Line took over the commercial operation of Surrey County Council route 479 from Countryliner, who had gone into administration earlier in the week.

[11] On 2 July 2021, All Quality Line operations ceased after remaining routes 413, 463 and S1 passed to Go-Ahead London at the end of their contracts.