There was little between the sides in what was hard fought first 45 minutes but John’s 27th minute opener, after Geoff Horsfield had been pulled down by Kenny Milne, was enough to separate the two teams.

Birmingham fielded a strong side in what was the last game of their Scottish pre-season tour and gave a debut to ex-Wimbledon defender Kenny Cunningham.

But the home side took the game to their English opponents straight from the kick-off and looked sharp in the opening stages.

And it was Thistle who had the first real chance to open the scoring in the 10th minute when an attempted back pass by former Celtic player Olivier Tebily left Scott McLean clear through on goal.

The big striker had only keeper Nico Vaesen to beat but snatched at his shot and watched in despair as the ball went well wide of the Birmingham goal.

McLean did have the ball in the City net minutes later but the referee’s assistant ruled it off for an earlier offside.

As the first half wore on there was little between the teams, although Thistle looked to have more of an appetite for the game than their opponents who could not fashion a chance worthy of note.

But it was the visitors who took the lead in the 27th minute courtesy of a penalty.

Blues striker Horsfield, who looked offside, raced clear on the right and when he moved into the box he was sent flying by Jags midfielder Milne.

There was no doubt about the decision and John stepped up to score off Thistle keeper Kenny Arthur’s left hand post.

The visitors’ confidence lifted and they began to take control of the game, passing and moving with increased conviction.

As the tackles flew in and the game became more heated, there were chances at both end, with Blues defender Darren Purse and Thistle’s McLean both having decent efforts.