By Ashley Cowburn Labour has pulled off a stunning victory in a key by-election in a major blow to Rishi Sunak. Keir Starmer’s party won Kingswood – a Tory seat since the 2010 general election – with 11,176. There were 24,905 votes cast in Kingswood – a turnout of 37.11%. The result is likely to pile further pressure on the under-fire PM as national polls suggest the Tories could be on course for a historic wipeout at the next general election. At the last general election the former Tory MP Chris Skidmore won the Kingswood seat, near Bristol, with a massive majority of 11,220 and with 56% of …