Guest Stars Edward Hogg as Daimler Alex Ferns as Vic Collins Ian Whyte as Plague Doctor Nell Hudson as Louise Charles Armstrong as Mr Bannister Jonjo O'Neill as Mycroft Holmes Emma Cunniffe as Laura Machin Ansu Kabia as John Cooper Muna Otaru as Maggie Cooper Keira Chansa as Lucy Lucy Russell as Duchess George Potts as Compere Harriet Turnbull as Carla Machin Brooke Carter as Georgina Patrice Naiambana as Duke of Winchester Anouk Christiansen as Young Jessie Evie Lew-Davies as Young Bea Ameen Mustapha as William Cooper