'It was frank and open': Ex-Leeds and Reading man on fighting back from Portsmouth selection snub to become essential first-team pick

And after exclusion from Pompey’s squad for the first game of the season, the softly-spoken Irishman’s non-selection is now unthinkable.

The Blues currently possess League One’s joint-best defensive return, having recently gone 445 minutes without conceding.

It’s a remarkable record established since Regan Poole was joined by Shaughnessy in the centre of defence at Leyton Orient.

Overlooked for Ryley Towler in the curtain-raiser against Bristol Rovers, the recruit from Burton didn’t even make the 18-man squad in a 1-1 Fratton Park draw.

Since then, Mousinho’s men have let in one goal in five league games – and Shaughnessy has started them all.

The 27-year-old told The News: ‘I am old enough to know football can change very quickly for the good or the bad, so when things don’t go my way, like that first game of the season, I knew I had to get my head down and do things properly.

‘We had the Carabao Cup (Forest Green) days later, so there would be a chance for me to impress there – and thankfully the game went well and the manager made the change.

‘When the manager named the team a couple of days before Bristol Rovers and I wasn’t in it, I had a conversation with him afterwards.

‘It was frank and open, I just asked what I needed to do to get back into the team and the reasons for it. It was all very positive, no problems at all.

‘The message was to just continue what I’m doing, showing a good attitude and don't make it easy for them to leave me out of the squad.

‘Obviously there’s an element of being disappointed and frustrated, it was the first game of the season and I wasn’t in the team.

‘But it’s such a quick turnaround, you don’t have a lot of time to think too much about it or get too down, so it’s important to stay positive. A lot of it is a mental game.

‘It’s about getting past it, having conversations with my family and people that I keep close around me. It can change, you can’t get too down or too high.

‘Maybe I had that bit of disappointment to start off with, but then it was about bouncing back and proving I’m good enough to play in the starting XI.

‘I knew the opportunity would come, it was just down to me. Not worrying about other people, just worrying about what I can do and how I can perform.’

Shaughnessy is competing with Towler and the versatile Connor Ogilvie for a spot alongside the impressive Poole.

And he recognises great strength in depth across the Blues squad.

He added: ‘It's League One, there are loads of games, there will be a lot of changes, injuries and suspensions, so plenty of room for the team to change around.

‘The good thing is we’ve such a good quality squad here. I’m sure you could change 11 players and they could do the same job, you wouldn’t see much of a difference.’