Lewis attended Dalriada School and Trinity College, Dublin, before working as a freelance correspondent for BBC Northern Ireland and Harlech Television (HTV).

[1] He is the son of the quantity surveyor Thomas John Dudley Lewis, who came from Coleraine in County Londonderry, Northern Ireland, and his wife Doris (née Jones), who worked as a nurse.

[5] He was educated at the co-educational Dalriada School in Ballymoney in the north of County Antrim,[4][6] where he was bullied for a term because he was overweight and developed a severe stammer.

[5] After failing to enrol at the University of Cambridge,[5] he graduated with a Bachelor of Arts degree in Economics, Philosophy and Geography from Trinity College, Dublin (TCD), in 1967.

[9] After turning down two job offers in the advertising and public relations industries in England, he started working as a freelance reporter for BBC Northern Ireland in Belfast for ten months in 1967.

[2] In the early 1980s, Lewis wrote the "And finally..." segment, which featured positive stories at the end of each half-hour ''News at Ten'' bulletin.

[20][21] Lewis rejected an offer to present BBC Breakfast News but reportedly threatened his resignation from the corporation because he wanted to remain on prime time television.

He was called into the BBC in the early hours of that morning to present short national bulletins during a late night viewing of Borsalino about the car accident in Paris.

He returned home afterwards to get some sleep – expecting the Princess to pull through – only to be drafted in again in time for the special 6 am bulletin covering Diana's death.

[26][27] On 26 April 1999, he presented the Six O'Clock News bulletin with Jennie Bond on the day his co-presenter Jill Dando was murdered outside her home in West London.

[29] In 2000, Lewis presented Dateline Jerusalem,[6] and ''News 40: The Battle of Britain'', a week of nightly broadcasts reporting on events from six decades ago in a contemporary perspective.

[6] He is the founder and Executive Chairman of YourBigDay Ltd, which utilises ITN and Reuters archives to create birthday and anniversary videos spanning the last century.

[3] Lewis was made a director of the Independent Press Standards Organisation in 2014 and chaired an inquiry into the voluntary sector with regards to executive pay within it.

He was chairman of Families of the Fallen 2010–15; trustee of the Windsor Leadership Trust 2001–10, and is currently deputy chair of the Lord Mayor of London's Dragon Awards.

[6] He is a patron of Mildmay Mission Hospital, The Patchwork Foundation, the quarterly broadsheet Positive News, and Dementia UK.

[3] Lewis was appointed Commander of the Order of the British Empire (CBE) in the 1997 New Year Honours "for services to young people and the hospice movement.