Celtic signed Idah on a straight loan deal without a buy option inserted. There was plenty of interest in the 23-year-old in the winter window, with Hellas Verona seeing a loan to buy offer rejected as well as Championship clubs monitoring his situation.

That is likely to be the case again come the summer and Hartson, who played four games on loan at Norwich in 2007, has urged Celtic to try and sign him permanently in the off-season.

“Strikers are hard to find,” Hartson told the Glasgow Times. “The fee to get him now will have shot up because he’s been success at the club. But he’s scored big, important goals for Celtic this season.

“When he first came in you got the feeling some of the fans were a bit nonplussed. They looked at him playing for Norwich, maybe not getting a game every week, and it was a loan signing. But he has done well. He’s big and powerful, he can run in behind and he knows how to finish.

“If Celtic can get him for around the £4m or £5m mark, it would be a great bit of business. He could be a great signing. It can be a gamble with new signings, but Celtic will know what they are gong to get. They know he can make an impact in games, they know he can score big goals and handle the pressure.

“It’s a decision for Brendan Rodgers but I have been impressed with him. He seems a level headed boy who has a lot of attributes.”