Both Deila and Johansen are Norwegians, while Henderson played on loan for Norwegian club Rosenborg during the final two months of the 2014-15 season.
“It’s massive, after the games here in the papers in Norway there would be double page spreads on the match,” the 19-year-old told The Glasgow Evening Times.
“Everybody who spoke to me always asked about the gaffer here and obviously Stefan as well and previous Norwegian players who have played.
“They were extremely interested and Celtic is a world-wide club. I was expecting that when I went over there, all the questions about the manager and Stefan.”
Henderson’s comments underline just how big Celtic are and how popular they are globally.
Celtic are one of the biggest clubs in the world and have a global fanbase, and it seems that youngster Henderson got a first-hand feel of that.
The Bhoys, though, continue to struggle to make themselves regulars in the Champions League, as last season they failed to get into the group stage of Europe’s premier club competition.
The Hoops will be aiming to rectify that this time around and will be determined to get the past qualifying rounds, which start this month.
It will not be easy for Celtic, though, but hope springs eternal.