The irony is that it seemed Armstrong couldn’t wait to get out of Parkhead and move to the Premier League.
He constantly stalled on a new deal and moved to Southampton for around £7 million in the summer of 2018.
However, the Scotland star was gushing in his praise for his old club as he and Elyounoussi sat next to each other at the club’s Staplewood training base when news emerged that Neil Lennon was in the market.
Elyounoussi also got advice from Norway team mate Kris Ajer and Fraser Forster.
After being snubbed by Ralph Hasselhuttl he has become born-again at Parkhead with seven goals and five assists and win the Ladbrokes player of the month for October. He said: “I spoke to Stuart, of course, as we’re team mates at Southampton and he was able to tell me things that I didn’t know about the club.
“He told me so many good things about Celtic. And it was perfect that he sat next to me in the Southampton training ground dressing room.
“Of course, I had also spoken with Kris Ajer about Celtic too so I had a good knowledge of what I was coming into.
“I didn’t look at it as a step down, going from the English Premier League to the Scottish Premiership.
“I needed to get game time. I needed to get minutes on the pitch. I feel Celtic have brought my confidence back. I’m scoring goals and I’m really happy.
“I expected to do well. I came up here to help the team to create chances and score goals to help them win games.
“So, I’m not surprised. I know the quality I have and I think the manager knows that as well.
“So, with his belief and trust in me and the help of the coaches too I feel I am bringing what I can to the team.
“I’ve scored seven goals so far and I’m happy with that but I feel I could have scored even more.”
Elyounoussi caused anxiety when he was sent home by the Norwegian national team with an injury last week – especially with a League Cup Final against Rangers coming up on 8 December.
However, he has revealed that it’s a small knock on his foot. He is a doubt for Livingston on Saturday and might not be risked but should be ready for Rennes in the Europa League next week.
The 25-year-old, who moved to Saints from Basel last year for £16million, said: “I actually picked up the injury a couple of weeks ago against Hibs in the League Cup semi-final.
“Then I had to go with the national team and it didn’t really have enough time to heal.
“So we had a look at it and it was decided I needed a rest. But I think it will be alright.
“The League Cup Final is a chance to win some silverware early in the season and I can’t wait for this game.
“I watched the first Old Firm game of the season and the atmosphere was amazing.
“It’s something I really want to experience so I’m really looking forward to this game.”
Of course, Scotland could meet Norway in a winner takes all showdown for a place at Euro 2020 with Ajer and Elyounoussi on one side and Callum McGregor, James Forrest and Ryan Christie on the other
He added: “It would be amazing if Norway was to play Scotland for a place at Euro 2020.
“We’ve already been talking about that among the boys at Celtic.
“But we need to beat Serbia first in our semi-final and then see what happens.”