The son of an auctioneer and estate agent, Halliday was brought up in Welshpool in Montgomeryshire, and attended Oswestry School in Shropshire.

He worked briefly for Rolls-Royce in Hucknall, Nottinghamshire before being called up by the Army during the Second World War, serving in Iraq, Palestine and Egypt.

[3] Halliday joined the Shakespeare Memorial Theatre Company alongside Richard Burton, Michael Redgrave and Ralph Richardson.

He featured in episodes of other science fiction programmes including Out of the Unknown, UFO, Doomwatch and The Tripods.

Although the vast majority of his screen roles were on television, he appeared in a few films, including the Merchant Ivory drama The Remains of the Day (1993).