<Li> Miranda Raison as Harriet Hammond, Practice Manager (Series 3) </Li> <Li> Jessica Henwick as Amy Lang, a pupil who shadows Martha Costello, Clive Reader & Caroline Warwick (Series 3) </Li> <Table> <Tr> <Th_colspan="2"> Series </Th> <Th> Episodes </Th> <Th_colspan="2"> Originally broadcast </Th> <Th_colspan="4"> DVD release date </Th> </Tr> <Tr> <Th> Series premiere </Th> <Th> Series finale </Th> <Th> Region 2 </Th> <Th> Region 1 </Th> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> 6 </Td> <Td> 22 February 2011 </Td> <Td> 29 March 2011 </Td> <Td> 11 April 2011 </Td> <Td> 12 November 2013 </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> 6 </Td> <Td> 15 May 2012 </Td> <Td> 20 June 2012 </Td> <Td> 25 June 2012 </Td> <Td> 1 March 2016 </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> <Td> 6 </Td> <Td> 24 February 2014 </Td> <Td> 31 March 2014 </Td> <Td> 7 April 2014 </Td> <Td> 3 January 2017 </Td> </Tr> </Table> <Tr> <Th_colspan="2"> Series </Th> <Th> Episodes </Th> <Th_colspan="2"> Originally broadcast </Th> <Th_colspan="4"> DVD release date </Th> </Tr>

How many series of silk have been made
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