Wallace works in media consultancy in London, advising on script development and programme acquisition for broadcasters and production companies worldwide. His first published work was the short story Five Dimensional Thinking in the Big Finish Productions Bernice Summerfield short story collection, Life During Wartime (Big Finish Productions, 2003), edited by Paul Cornell. The short story UNIT Christmas Parties: First Christmas followed in the Short Trips collection A Christmas Treasury (Big Finish Productions, 2004), also edited by Paul Cornell.

Wallace's first novel, Fear Itself was published in 2005. The novel, which Wallace says was inspired by Ian Rankin’s Inspector Rebus novels, has had a positive reception from reviewers and fans alike.

He is the editor of the 2006 short story collection Collected Works, another in the Bernice Summerfield range produced by Big Finish. His first audio play, The Judas Gift, was released in 2007.

Novels

• Fear Itself (BBC, 2005)

Novellas

• The Irredeemable Love (in Miss Wildthyme and Friends Investigate, Obverse Books, 2010)

Short Stories

• Five Dimensional Thinking (in Life During Wartime (Big Finish Productions, 2003)
• UNIT Christmas Parties: First Christmas (in A Christmas Treasury, Big Finish Productions, 2004)

As editor

• Collected Works (Big Finish Productions, 2006)

Audio plays

• The Judas Gift, (Big Finish Productions, 2007)