 The remainder of the regular cast includes Una Stubbs ( who has known Cumberbatch since he was four years old , as she had worked with his mother Wanda Ventham ) as Mrs Hudson and co @-@ creator Mark Gatiss as Mycroft Holmes . <unk> Robinson , Jonathan Aris and Louise Brealey play the recurring roles of Sergeant Sally Donovan , Philip Anderson and Molly Hooper , respectively . 
