Henry Slade was the shock omission from England coach Steve Borthwick's 33-man squad for the World Cup on Monday.The Exeter centre was part of England's run to the final four years ago and had appeared in 30 of the last 37 Tests.However, he has missed out to Joe Marchant, who impressed despite a disappointing 20-9 defeat to Wales on Saturday."There have been a number of very difficult selection decisions to make," said Borthwick."Some very good players have missed out on selection such has been the competition for places over the last eight weeks and more of preparation."Borthwick also defended the decision to name his squad early with further warm-up matches against Wales, Ireland and Fiji to come before the deadline later this month."We believe that announcing the squad a little earlier than otherwise might have been the case, brings a clarity and certainty to the group, allowing the players as much time as possible to settle and develop as a squad," he added.READ | Retallick named in All Blacks' World Cup squad after injury scareThe exclusion of Alex Dombrandt means that Billy Vunipola is the only specialist No 8 bound for France next month.Vunipola is chosen despite not having played since April because of two knee surgeries and missing the entire Six Nations after being frozen out by Borthwick on form grounds.Lewis Ludlam, Ben Earl and Tom Curry cover number eight and are present among a large contingent of versatile back five forwards that includes rookie Leicester duo Ollie Chessum and George Martin.Other big names to miss out are wings Jonny May and Joe Cokanasiga, both of whom played at the World Cup four years ago.England will face Argentina, Japan, Samoa and Chile in Group D in what is regarded as the kinder