By Ashley Cowburn Rishi Sunak has failed a major test as Labour pulled off a stunning victory at a by-election in the former Tory safe seat of Wellingborough. Voters elected charity worker Gen Kitchen as the first Labour MP to represent the area in nearly 20 years as the party scooped the seat with 13,834 votes. The Tories previously won the Northamptonshire seat at every general from 2005 and last emerged with a massive 18,540 vote majority at the 2019 general election. The defeat in the early hours of Friday morning is likely to pile immense pressure on Mr Sunak with the Tories already facin…