It doesn't seem like he needed one. Campbell only turned 19 on Wednesday and the following day's game at Rugby Park was his first start in senior football but, based on first impressions, he does not come across as a shrinking violet wracked by self-doubt.
The striker has become the third Newcastle United youth player to arrive on loan in Paisley, following in the footsteps of Paul Dummett and Conor Newton. He has kept close tabs on the success enjoyed by his two friends - Dummett in particular - and has decided he fancies a bit of that for himself. If he fails to do so, it almost certainly will not be for the lack of trying.
Campbell is all of 5ft 7in with short ginger hair. He is a dyed-in-the-wool Geordie who grew up playing football for hours on Tynemouth beach, pretending he was Alan Shearer. He has played for England under-19s, and last season became Newcastle's youngest ever player to feature in European competition, but despite those landmarks he has retained a boyish, almost wide-eyed sense of enthusiasm and optimism. The money sloshing around the Barclays Premier League means it is nigh impossible for homegrown talent to break through but Campbell seems unfazed by the prospect.
"Newcastle haven't said anything but it's up to me to get myself into their plans," he said, almost matter-of-factly. "It's not for them to say to me, 'if you do well up there you'll get a chance'. I just want to show what I can do, score a few goals and go back and prove that I should be in the team.
"I just want to do what Paul's done. He came up here, he won a cup, he went back and got himself a new deal, scored against Liverpool, and started in the derby [against Sunderland]. It's been like a dream for him so my aim is to try to do as well as he did. I speak to him regularly and all he's got is positive memories from being up here so it was a no-brainer for me. As soon as I got the shout I was straight up."
Shearer was the deity of choice for most Geordies from the mid-1990s onwards and Campbell was no different. He recalls with clarity the day the pair crossed paths. "Alan Shearer was my hero and role model," he said. "Being a Newcastle fan he was the only person that you watched. He's the best Premiership goalscorer in history so it's not a bad inspiration to have. He's been there and done it all. Hopefully I can get to the same levels that he did.
"I met him one time when I was a mascot for a game against Bolton. I was part of the Junior Magpies club and we were on the bus when my name was drawn out the hat to be a mascot. We beat them 4-0 and it was my first ever away game. I was just a nipper, seven years old. I walked out with Shearer and warmed with up with Nikos Dabizas. It was a cracking experience."
Like Shearer and a host of other big names from the north-east, Campbell's early grounding came at Wallsend Boys Club. "They've brought plenty of players through, such as Shearer, Peter Beardsley, Alan Thompson and Michael Carrick. Plenty of legends from Newcastle have come through and hopefully I'm going to be the next one."
First, though, he has to make a positive impression at St Mirren. His debut goal was a promising start and Celtic tomorrow will give him another chance to shine. "It was a great feeling to get my first ever senior start," he added. "That was a confidence booster for me. You want to score as soon as you can so to do that 18 minutes in was a great start. I thought I had a tidy game overall but I could have done a lot better. I've been getting plenty of positive feedback from fans so that's nice to hear, but there's plenty more to come from me."