Pat, from Telford, revealed goalscoring hero Harry Maguire needed a new shirt printing minutes before the Sweden game because of a mix-up over his size.
The Leicester City centre-half has become a fans’ favourite for his World Cup exploits, with his goal against Sweden another step in a wonderful tournament from the giant defender.
Now the team’s kitman has revealed they were called into action before Saturday’s clash with the Swedes, because the shirt prepared for Maguire was the wrong size.
Writing on Twitter, the former West Bromwich Albion kitman said that the backroom staff only had three minutes to prepare the defender’s shirt.
Responding to a question about the biggest mistake in his career Frost said: "Wrong shirt size for Harry Maguire last match... had to print a new one in less than three mins... that’s pressure.”
The kitman also tweeted a picture of the team’s white kits for tomorrow’s semi-final clash against Croatia, printed with the date of the match below the Three Lions badge.
Asked if the achievement of knockout victories over Colombia and Sweden had sunk in, Frost said the team has one goal, and responded with: "Everyone is focused on one thing.”
The kitman has also been flying his own West Bromwich Albion flag in the stands at each of the England games, going out ahead of kick off to hang it off the railings.
Earlier in the tournament Frost told how Tottenham midfielder Eric Dier, who struck the winning penalty against Colombia, had enjoyed a hero’s welcome back to the dressing room after completing his round of media interviews about the game.
Alongside a video of hundreds of England fans cheering the victory after Dier slotted home the spot-kick Frost posted: "This was the England dressing room when Eric Dier walked in after doing interviews after the penalty shoot out.”
The kit man’s Twitter account - @KitmanPat - has attracted a large following for his behind the scenes insights into the Three Lions’ quest for long-awaited World Cup glory.
Earlier in the tournament Frost showed off Harry Kane’s hat-trick boot following the 6-1 win over Panama and the striker’s two man of the match awards.
Alongside the picture of the skipper’s boot he added the message "Just gone to clean this little sucker . . . it’s going to have to wait . . . it’s still too hot to hold”.