The Englishman, still without a senior appearance, has spent consecutive seasons on loan at Aston Villa, keeping 22 clean sheets over the 2017/18 campaign.
He has impressed Steve Bruce to the extent that the Championship side want to sign him on a permanent basis.
But according to the Express and Star‘s Matt Wilson, Johnstone will move to West Brom – who need a replacement for Ben Foster – rather than Villa, who are unable to complete a permanent deal due to an ensuing financial crisis.
Before Villa, Johnstone traversed the lower divisions relentlessly, spending periods at Oldham, Scunthorpe, Walsall, Yeovil Town, Doncaster and Preston North End. Now, at the age of 25, he needs to establish himself somewhere, to get his feet under the table.
And at West Brom he will have the chance to do exactly that in the Championship – an arena in which he looks totally relaxed – as Foster’s replacement. The Baggies suffered relegation after several months of Alan Pardew last season but their organisation at the back is nonetheless an unyielding feature of the team. He will be expected to hit the ground running.