CBBC has signed on for two more 24 x half-hour series of Doctor Who spin-off The Sarah Jane Adventures.

Created by Russell T. Davies and featuring Doctor Who’s famous companion, Sarah Jane Smith, The Sarah Jane Adventure is produced by BBC Cymru Wales and debuted in 2007, with viewing figures continuing to grow year-on-year.

The fourth series, set to air this fall, will again star Elisabeth Sladen as Sarah Jane and young actors Tommy Knight, Daniel Anthony and Anjli Mohindra return as popular regulars Luke, Clyde and Rani. Production on the fourth season gets underway in Cardiff later this month with series three producer Nikki Wilson stepping up alongside Russell T. Davies as executive producer, and new producer Brian Minchin joining the team.

The fifth series will go into production in 2011 for transmission later that year.

Writers on the fourth series include Phil Ford (also co-producer), Joseph Lidster, Rupert Laight, Gareth Roberts and Clayton Hickman.