First mentioned in Lethal White, Valentine Longcaster is Charlotte Campbell’s younger stepbrother. He is one of her favourite siblings, along with Sacha.

In 2009, Strike and Charlotte went to the Epsom Derby with Valentine and Sacha. Strike is broke at the time, having just started his detective agency. Charlotte wins £2500 on a bet and insists on champagne.

In The Ink Black Heart, Strike encounters Valentine in Annabel’s club on Berkeley Square on New Year’s Eve 2014, whilst conducting surveillance on Legs with subcontractor Midge. Valentine has a long sweaty fringe and dilated pupils, and Strike notices a trace of white powder inside one nostril.

Valentine tells Strike that Charlotte’s husband Jago Ross is going to name Strike in his divorce case. Strike doesn’t think much of it at the time, but later has no choice but to set the agency’s subcontractors onto getting dirt on Jago.

In Annabel’s, Valentine is with a friend called Madeline Courson-Miles, a successful jewellery designer who looks like Robin Ellacott. Valentine tells Strike that Madeline thinks Strike is sexy.