Delamere has appeared in Agatha Christie's Poirot: Evil Under The Sun in which she played Arlena Stewart, an actress who is murdered on a beach. She was featured in the Cadfael episode "The Holy Thief" and appeared in the BBC crime show Waking The Dead as Elaine Ashcroft, again playing a murder victim in the fourth season finale Thin Air. She also had a role in the television drama The Chatterley Affair and has appeared in Torchwood. She played the recurring character Marion James in the fifth series of Waterloo Road. In episode 1 of the 2006 third season of the TV series Blue Murder, Louise played a double role as Lynne Aziz, an attractive strong calculating attorney, with a brief appearance as a disturbed twin sister, Paula Hickson, whose murder by her husband in the first few minutes of the show instigates mass confessions from her family for the similar murder of her husband upon his release from prison.
Delamere is married to Stephen Mangan. They have two sons: Harry (October 2007) and Frank (2010). She has three brothers; her younger brother is the actor Matthew Delamere, and one of her older brothers is the director Robert Delamere.