In the past few weeks, Mulgrew has been thrown into midfield bearpits and been asked to cope with Marouane Fellaini, Axel Witsel, Xavi, Andres Iniesta, Sulley Muntari and Nigel de Jong. He handled all of them nervelessly, which is more than could be said of the time he had to type in a phone number and call the Scotland manager.
June 8 loomed large on the Mulgrew family calendar. It was the day chosen for Charlie to marry his fiance, Alana. A few months earlier he had realised with some dismay that it was also the day after Scotland took on Croatia in the World Cup qualifying campaign, meaning he could not play if selected. When it became obvious that he was likely to be included in Gordon Strachan's squad for Zagreb Mulgrew had to bite the bullet and let him know. "It was worrying at the time," he said yesterday. "I wasn't looking forward to the phone call to tell him, to be honest. I just went for it one day and got the phone call out of the way. He was very good and understanding about it, but I knew I would have to work hard to get back in. He didn't say I would definitely be in the next squad; I don't think any manager would say that. As a player, you know you have to work hard to get in any Scotland squad."
Robert Snodgrass scored the only goal in the most unlikely of Scotland wins, of course. Whatever last- minute wedding preparations there were, Mulgrew excused himself from them to watch his team-mates in Zagreb. "I saw the game and it was a great performance. Nobody really gave us a chance that night, so that made it even better. You can't really [allow yourself to] think that missing a game like that will make it more difficult for you to get into the next Scotland squad. You have to stay positive and believe you can get into the next one."
Four months into the Mulgrews' marriage, Scotland take on Croatia again, this time at Hampden on Tuesday evening. The squad assembled yesterday afternoon although Jordan Rhodes became the first call-off. The Blackburn Rovers striker has a groin injury and is also still receiving painkilling injections after breaking a bone in his hand while with the squad for last month's double-header against Belgium and Macedonia.
Tuesday's game is Scotland's last in Group A, of course. A campaign in which both a manager and the prospect of reaching Brazil were lost has become merely a vehicle for experimentation and for momentum to be built before the Euro 2016 qualifiers begin next autumn.
The change of manager came after Craig Levein's teams had drawn with Serbia and Macedonia and then lost to Wales and Belgium. Strachan began with defeats to Wales and Serbia but remarkably won that summer visit to Zagreb. After a home loss to the Belgians, the most recent outing delivered another away win, in Macedonia. Levein took two points from four games, and Strachan has six points from five. It was, of course, the group in which Levein had said each individual fixture could be considered winnable for Scotland.
"Maybe things could have been a bit different but there's no point in looking back," said Mulgrew. "You've got to look forward. We've got this last game and hopefully we can get a positive performance and result, and then to look to the next campaign. That's what we can affect, we can't look back."
Mulgrew playing in a central midfield role is not exactly the revelation it has been presented as in recent weeks - he has periodically appeared there at previous points in his career - and the absence of Darren Fletcher, James Morrison and Joe Ledley for varying periods of time created opportunities for him with both Celtic and Scotland. But he has played with poise and used the ball well alongside Scott Brown, earning considerable praise. "I've been enjoying it," he said. "It suits me in many ways to get on the ball and play in there and it helps to play with somebody like 'Broonie', who's such a good player. I've really been enjoying it and I hope I can keep playing there and play well.
"They have been tough games really. It was hard to get a touch against Xavi and Iniesta [when Barcelona won 1-0 at Parkhead last midweek] but these are the types of games you want to be involved in and the type of players you want to measure yourself against. That's why we are in football.
"They are fantastic, technical players who keep the ball so well. But it's not just that. I have played against other great players who keep the ball, but the way Barcelona work when they don't have it is incredible. But coming through it is something that gives you confidence."