Suggestions by @cosmolover

Toby Stephens

as Lord Peter Wimsey in Unnatural Death

Score: +1

Julian Rhind-Tutt

as Perkins in Have His Carcase

Score: +1

Honeysuckle Weeks

as Harriet Vane in Have His Carcase

Score: +1

Honeysuckle Weeks

as Harriet Vane in Strong Poison

Score: +3

Emilia Clarke

as Marjorie Phelps in Strong Poison

Score: +2

Jack Davenport

as Inspector Charles Parker in The Unpleasantness at the Bellona Club

Score: -1

Adrian Lester

as Inspector Charles Parker in The Unpleasantness at the Bellona Club

Score: -1

Jo Woodcock

as Ann Dorland in The Unpleasantness at the Bellona Club

Score: +1

Ruby Bentall

as Ann Dorland in The Unpleasantness at the Bellona Club

Score: -1

Emilia Clarke

as Marjorie Phelps in The Unpleasantness at the Bellona Club

Score: -1

Michelle Ryan

as Sheila Fentiman in The Unpleasantness at the Bellona Club

Score: -1

Vicky McClure

as Mrs Morcombe in Have His Carcase

Score: +1

Joanna Scanlan

as Mrs LeFranc in Have His Carcase

Score: -1

George MacKay

as Lois DeSoto in Have His Carcase

Score: +1

Gary Carr

as Antoine in Have His Carcase

Score: +1

Jason Watkins

as Inspector Umpelty in Have His Carcase

Score: -1

Daniel Mays

as Henry Weldon in Have His Carcase

Score: +2

Ashley Jensen

as Mrs Weldon in Have His Carcase

Score: +1

Emma Fielding

as Mrs Weldon in Have His Carcase

Score: +1

Joseph Kloska

as Mervyn Bunter in Have His Carcase

Score: +1