Grant began a career in theatre at the age of seven when he made his stage debut in Danton's Death at the National Theatre.   In the same year Grant was cast in Jim Henson's The Dark Crystal and for the next twenty years acted in film, television and theatre in pieces such as March of the Falsettos (Albery), Into the Woods (Phoenix), Hamlet (NT) and Miss Saigon (Theatre Royal Drury Lane). He trained at the Central School of Speech and Drama (graduating 1994 with a BA in acting) and for a while alternated between acting and writing and performing in rock bands and with his own solo singer/songwriter material.

In 2003 Grant Olding was invited by the Bridewell Theatre's artistic director Clive Paget to become their first composer in residence after he'd heard Life - a musical with sentences, a show that Grant wrote during his time in Miss Saigon. At that point Grant stopped acting and became a full-time composer/lyricist.

Whilst at the Bridewell Grant wrote three musicals, A Celebrity Chef Ate My Hamster! which ran for four weeks as part of the lunchbox season, Beyond the Sea which was produced twice by the Bridewell's Youth Music Theatre company, and Three Sides which was given a workshop production and had extracts from it shown as part of the Creativity Outbreak season and at the Farewell/Gala Concerts. Also at the Bridewell Grant wrote scores for the David Ives play All in the Timing, Mamet's Reunion , and Shakespeare's Twelfth Night .   Other scores written during this period include Romeo & Juliet (Southwark Playhouse), The Blue Diamond of Azkabar (Hazlitt Theatre and tour), the musical Born of Glass (NYMT, Lyric Belfast), and Much Ado About Nothing (open air tour of castles in Kent).

In 2004 Grant was commissioned by Sir Alan Ayckbourn's Stephen Joseph Theatre to write Spittin' Distance , a one act musical set at a professional cherry-pit spitting contest (based on a real life event).   Spittin' Distance was produced in March 2005 at the SJT as part of the micro-musicals season.   The National Theatre Studio then put Grant & Toby on attachment whilst they expanded the piece to a full length musical with an ensemble.

Also in 2005 Grant wrote the score for Twelfth Night (touring castles in Kent), whilst Three Sides played for one night only at the Shaw Theatre and A Celebrity Chef Ate My Hamster! had another outing at the Chichester Fringe Festival.   In 2006 Grant wrote the score for Nicholas Hytner's production of Samuel Adamson's new play Southwark Fair at the National Theatre, a show that he's very proud to have been a part of.   And in March, his songs were enthusiastically received in Not(es) From New York at the Duchess Theatre - the first in the series of concerts to focus on British musical theatre composers (Charles Miller was the other featured writer), and the first time that Grant's work had been heard in a West End Venue.

The Summer of 2006 saw Grant write scores for Macbeth and The Importance of Being Earnest (Changeling Theatre, tour), and three of Grant's musicals hit the stage; Yeti - an abominamusical opened to critical acclaim and full houses in Edinburgh, Tracy Beaker Gets Real started it's first national tour at the Nottingham Playhouse, then going on to play at 12 other venues before the end of the year, and Three Sides was performed both at the Finborough Theatre in London and at the 45th Street Theatre in New York as part of the New York Musical Theatre Festival. Three Sides got rave reviews in NYC, and won Grant a NYMF award for excellence in Musical Theatre Writing (lyrics), plus an honourable mention in the music category.

Back at the National Theatre, Grant wrote the scores to Nicholas Hytner's productions of Ben Jonson's The Alchemist, and The Man of Mode which got the fantastic reviews they deserved. Meanwhile, in early 2007, a new version of Tracy Beaker Gets Real (including five brand new songs) took to it's second tour, opening at the Bristol Hippodrome and taking in most major number one venues, with over 125,000 people seeing the show in it's six month run. Grant then worked at the West Yorkshire Playhouse writing a new score for Amanda Whittington's Bollywood Jane, directed by Nikolai Foster. In the summer Grant's new musical version of The Beggars Opera toured open air venues in Kent and was a big hit with audiences and critics. 101 Dalmatians at the Royal and Derngate finished off the year with Grant writing five new songs and over an hour's worth of music to Debbie Isitt's version of Dodie Smith's beloved tale.

Jan 2008 saw Grant back at the West Yorkshire Playhouse, working with director Nikolai Foster again on Louise Page's wonderful play Salonika. Grant then began work on a new musical - commissioned for the National Theatre by Nicholas Hytner. In March Grant worked at the Watermill Theatre in Newbury on London Assurance which then toured for seven weeks. Most of 2008 will be taken up with the writing of the new musical Simply Cinderella for Curve Theatre and of the NT musical.