Aston Villa are looking for a new goalkeeper this summer, and Sheffield Wednesday stopper Keiren Westwood could be an option.
Johnstone spent the back end of last season on loan at Villa and was widely expected to complete a transfer to the Midlands club this summer.
However, it seems that Boro have hijacked the deal – which leaves Villa having to re-start their search for a new stopper.

The claret and blues’ current goalkeeping options look very slim, with Jed Steer seemingly the best custodian available to Bruce as things stand.
Villa will do well to find a player of Johnstone’s quality available at a similar price of £2.5 million, but Sheffield Wednesday may just have a solution for them.
It seems that Boro boss Garry Monk has decided to go for Johnstone instead, but if Westwood is potentially available then he should be considered by Villa.
Westwood has been one of the best goalkeepers in the Championship over the past two seasons, and would offer an experienced option for Villa.
It would be a shock if Wednesday were to sell up, but Boro seemingly thought a deal was possible – and Villa should test the water at Hillsborough, to see if Carlos Carvalhal would be open to listen to offers for the Republic of Ireland international.

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