After gaining recognition in Great Britain through the Z-Cars (1962–78) police series on BBC1, he appeared in many other television and film roles.

[4] Ellis became established as the company's young male lead in such plays as April in Assagh, where he was cast as McFettridge (1954), Is the Priest at Home?

[citation needed] While continuing as an actor in the main company, he also undertook the management of the group's summer theatre in the port town of Larne, north of Belfast.

It was an "Angry" play deemed so controversial and sexually charged that the BBC gave a warning before the transmission that it was "unsuitable for people of a nervous disposition".

[2] In addition he appeared in a January 1967 episode of the Z-Cars spin-off Softly, Softly ("Barlow Was There: Part 3: Mischief"), which reunited the now DC Lynch with his former Newton colleagues, Barlow (Stratford Johns), Watt (Frank Windsor) and Blackitt (Robert Keegan).

[2] He appeared in Till Death Us Do Part, in Doctor Who, In Sickness and in Health, Ballykissangel, Playing the Field, One By One and the cult sitcom Nightingales, with Robert Lindsay and David Threlfall.

[11] Ellis also contributed cameos to popular series such as Boys from the Blackstuff by Alan Bleasdale, Only Fools and Horses, The Bill, Casualty, Boon, Common as Muck, Birds of a Feather, Lovejoy and Heartbeat.

In July 2008, Queen's University Belfast awarded Ellis an honorary doctorate as part of its centenary celebrations.