While details of Anna’s character are being kept under wraps, bosses have revealed her on-screen alter-ego will be called Rachel.
The star previously played Ruby Button in the Channel 4 soap, and also appeared as Romilda Vane in three of the ‘Harry Potter’ films.
The series will air on BBC Three later this year, and Anna joins a cast that includes former ‘Corrie’ actress Katherine Kelly.
‘Class’ will be set in Coal Hill school in contemporary London, and four newcomers - Greg Austin, Sophie Hopkins, Fady Elsayed and Vivian Oparah - will play sixth-formers.
‘Doctor Who’ showrunner Steven Moffat has previously teased the series, describing it as "dark and sexy".
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