He plays the mechanoid Kryten in the sci-fi television sitcom Red Dwarf and formerly presented the engineering gameshow Scrapheap Challenge.

He has also founded and hosts a YouTube series, Fully Charged,[2] which has grown into a company that puts on EV and "Everything Electric" conventions in the UK, USA, Canada, Australia and Europe.

[1] Llewellyn's first foray into the world of show business started out as a hobby, organising a few amateur cabaret evenings in a riverside warehouse overlooking Tower Bridge in London.

[3] Within six months, he had stopped working as a shoemaker and started performing professionally with the group alongside Bernie Evans, Nigel Ordish and Graham Allum.

Llewellyn's skills as a physical performer encouraged Rob Grant and Doug Naylor to write him additional characters for the series, namely Jim Reaper ("The Last Day"), Human Kryten ("DNA"), Bongo ("Dimension Jump"), Able ("Beyond A Joke") and the Data Doctor ("Back in the Red").

In Red Dwarf, he worked hard to get the more technically difficult lines right because the series tried to be factually accurate in reference to scientific theories.

[6] Llewellyn was also the only British cast member of Red Dwarf to originally participate in a proposed American version, though other actors such as Craig Charles and Chris Barrie were also approached to reprise their roles.

In 1992, Llewellyn appeared in "Parade", the fourth episode of series two of Bottom, as a wounded Falklands War veteran named Mr. N. Stiles.

In January 2011, Llewellyn appeared on Celebrity Mastermind answering questions on the specialist subject of electric cars; he has expressed an interest in working on a television series about technologies that we might use in the future.

Prior to becoming a comedian, Llewellyn served an apprenticeship and became a professional shoemaker, working at James Taylor & Son and John Lobb Bootmaker in London.

[12] On the evening of 1 July 2009, while Llewellyn was en route to deliver Carpool footage to his editor, another vehicle hit him side-on at a junction in Gloucestershire, writing off his Toyota Prius and rendering him unconscious for around ten minutes.