By Dan Marsh Gareth Southgate should remain in his post as England manager rather than entertain interest from Manchester United, according to Graeme Souness. Southgate, 53, has been in charge of the national team since 2016 and led England at three major tournaments, reaching the World Cup semi-finals back in 2018. He also oversaw the Three Lions’ run to the Euro 2020 final, where they lost on penalties to Italy at Wembley. As it stands, this summer’s European Championships will be the final tournament Southgate oversees with his contract set to expire in December. The Football Association wo…