Quentin became known for her television appearances: portraying Dorothy in Men Behaving Badly (1992–1998), Maddie Magellan in Jonathan Creek (1997–2000), and DCI Janine Lewis in Blue Murder (2003–2009).Quentin received an Ian Charleson Award commendation for her Masha in The Seagull at the Oxford Theatre Company in 1991.[5] Her early stage work had also included appearing in the chorus of the original English production of the musical Les Misérables in 1985.

In July 1996, Quentin released a single, a cover of the Exciters' hit "Tell Him", with her Men Behaving Badly co-star Leslie Ash under the name of "Quentin and Ash". The single reached number 25 in the UK Singles Chart and spent 3 weeks in that listing.[6] From 1997 until 2000 Quentin starred alongside Alan Davies in Jonathan Creek playing investigative journalist Maddie Magellan, who uses Jonathan's mind to solve murder mysteries.