The original “one-off” episode aired over New Year 2012 to mark the 25th anniversary of the very first Morse episode. and drew a consolidated audience of 8.2m.
The four new films have been written by Lewis creator and Morse writer Russell Lewis and co-star Roger Allam as Endeavour’s senior partner, Detective Inspector Fred Thursday.
Joining the series is Sean Rigby in the role of young PC Strange – the character who appeared in the original Morse series, played by James Grout.
James Bradshaw will return as Dr Max Debryn and John Thaw’s daughter Abigail will make further guest appearances as Dorothea Frazil.
Supporting cast include Anton Lesser (The Hour, Garrow’s Law, The Scapegoat) as Chief Supt Reginald Bright and Jack Laskey (Sherlock Holmes: A Game of Shadows) as DS Peter Jakes.
Sunday 14 April at 8pm on ITV.