England are preparing to finalise their first Test squad of the summer, with a host of county hopefuls waiting to find out if they have done enough to earn a call. The senior management group of Rob Key, Brendon McCullum and Ben Stokes remained in place despite the regime hitting a new low over the course of their 4-1 Ashes defeat, but some changes on the field are impossible to avoid. With Marcus North’s appointment as the new national selector set to be formalised, the panel will soon convene to make its picks to face New Zealand at Lord’s from June 4. They have five rounds of the Rothesay County Championship to inform their decisions, albeit with McCullum yet to arrive in the country, and a handful of issues to wrestle with. There is a clear vacancy at opener, where Zak Crawley has surely relinquished his fingertip grip on the shirt. A divisive cornerstone over the past four years, he has averaged just 19.50 in 10 innings for Kent in Division Two and has burned through whatever leeway he had left.…