SundanceTV and BBC One have set key casting for six-part drama series The Split from Emmy and BAFTA-winning writer Abi Morgan (The Hour) and BAFTA-winning executive producer Jane Featherstone (Broadchurch, Humans, River), which begins production next week in the UK. Leading the ensemble cast is Nicola Walker (River, Last Tango in Halifax), alongside Meera Syal (Goodness Gracious Me), Stephen Mangan (Episodes), Fiona Button (Lip Service), Deborah Findlay (Leaving)…