JAMES Tomkins believes ‘squad depth’ will be key to Coventry City’s promotion chances under Frank Lampard this season. Tomkins made more than 200 appearances for boyhood club West Ham United and also spent time on loan at Derby County before finishing his career at Crystal Palace. Sky Blues head coach Lampard also came through the ranks at West Ham and later took charge of Derby in his first stint as a manager. And Tomkins, who won promotion to the Premier League with the Hammers in 2011/12, insists Coventry’s squad depth will play the biggest part in the club’s quest for promotion.