Onions back in Test frame after injuries hit Anderson and Tremlett

Having last played a Test in early 2010, Graham Onions, the Durham bowler, has taken 39 wickets in his county's title challenge this season (Getty)

England may need to offer further evidence of their strength in depth following enforced changes yesterday to their squad for the fourth Test. Jimmy Anderson, one of the heroes of Edgbaston and of recent campaigns in general, has an injured quadriceps, and Chris Tremlett failed a fitness test on his back.

Although the selectors assume Anderson will recover by the start of the match at The Oval on Thursday, they have called up the Durham fast bowler, Graham Onions, as cover. Onions last played a Test early last year against South Africa at Cape Town.

In Bangladesh two months later he went home with a back injury which was later joined by a knee complaint. Surgery forced him out of the game for a year and, although his first steps back were tentative, he has taken 39 wickets in Durham's Championship challenge this season.

Onions was impressive in his brief international career to date, having the precious asset of bowling metronomically on off stump from close to the wicket. When he played for England Lions at Derby in May he was still short of match hardness but the selectors are presumably content with his development since.

It is unlikely that Onions will play. An unchanged side still looks most probable but if Anderson fails to recover with what is described as niggle, Steve Finn, already in the squad, would feature. But for Onions, the news is that he is back in contention.

Further evidence of England's depth was provided yesterday with the announcement that the team's coach, Andy Flower, will be rested for the one-day international against Ireland on Thursday next week. The team leave on Wednesday (after finishing their Test summer on Monday if the match goes the distance) and Flower will have the opportunity for a week's holiday.

The team's fielding coach, Richard Halsall, a crucial member of the backroom staff, will take over Flower's official title as team director in Dublin. Flower has often stressed the need for selective rest and this shows his mature confidence.

England will be even keener to beat Ireland after their sensational World Cup defeat in March. The squads for the limited-overs matches will be announced on Saturday.

* Yorkshire captain Andrew Gale will miss the rest of the season with a broken arm, dealing a major blow to his team's chances of escaping County Championship relegation.