Alex Mitchell also appeared off the bench in all three British and Irish Lions Tests in Australia last summer England's first-choice scrum-half Alex Mitchell has been ruled out of the remainder of their Six Nations campaign with a hamstring injury suffered in Saturday's 42-21 defeat by Ireland. Mitchell has started England's last 10 Six Nations matches having secured his spot as head coach Steve Borthwick's preferred number nine in the run-up to the 2023 Rugby World Cup. Leicester's Jack van Poortvliet replaced Mitchell off the bench in the 24th minute at Allianz Stadium. Bath's Ben Spencer is another scrum-half in the wider squad, while Sale's Raffi Quirke has been called up as additional cover. Mitchell's absence raises the prospect of an entirely new half-back partnership starting 7 March's meeting with Italy, with George Ford coming under pressure from fly-half rival Fin Smith after an underwhelming performance against Ireland.…