It’s 40 years this May since a teenage Pat Bonner scribbled his name on to his contract with Celtic as Jock Stein’s final signing for the club.

“40 years?,” he reflected as this decorated Irish keeper mulled over the passing of time. “That’s why this t-shirt doesn’t fit,” added Bonner with a smile as he hastily contorted himself into an officially branded William Hill garment which was not quite made-to-measure by Benny Hamish.

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With well over 600 appearances for Celtic, this one-club man was a perfect fit between the sticks. In front of him, meanwhile, Bonner looked on as a variety of prolific poachers rattled in goals left, right and centre.

“When I played in the early 1980s, Charlie Nicholas and Frank McGarvey used to have a competition to see which of them would be the first to hit 30,” he recalled.

A custodian discussing affairs concerning strikers may be a breach of the small print in the charter of the Goalkeepers Union but, with the current Celtic net-busters not quite emulating the profitable pickings of recent seasons, Bonner has no qualms about passing comment.

With the domestic campaign rumbling to a conclusion, neither Moussa Dembele, Leigh Griffiths or Scott Sinclair have broken into double figures on the league goalscoring charts.

Yes, there have been injuries to contend with but, ahead of this weekend’s William Hill Scottish Cup semi-final with Rangers, Bonner wants to see more from those charged with unleashing the heavy artillery on the attacking frontline.

“The goalkeepers and defenders at Celtic, the guys who break up the play and stop the other team scoring, are never the ones the fans will talk about in the future,” he said. “It’s the creative players who get the plaudits but you need to perform week-in and week-out to be elevated to that status.

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“How are they going to be remembered in years to come? You think back to goalscorers like Stevie Chalmers, Kenny Dalglish, Charlie, Frank McAvennie and Henrik Larsson and the men who created the chances; Jimmy Johnstone, Tommy Burns and Paul McStay.

“Danny McGrain was a creative right-back, just as Kieran Tierney is on the opposite flank nowadays. They’re the ones supporters remember, not the holding midfielders or the centre-backs or goalkeepers.

“To play as a striker for Celtic Football Club, you have to be good all the time and that’s what Moussa Dembele and Leigh Griffiths should be thinking about; how am I going to be remembered as a proper striker for this fantastic club?

“I’m not criticising them. What I’m saying is that they need to be consistently effective. Injuries can affect players but Henrik and Charlie both came back from broken legs and produced the goods again.

“Moussa Dembele is a young man with brilliant attributes. For me, though, he has to do it more often.

“I’ve no doubt that he’ll go out on Sunday and he’ll show his quality again but I want to see him doing that on a regular basis.

“When I look at the goalscoring charts and the top Celtic scorer has nine goals in the league, I question that. I don’t think that’s ever happened before in a championship-winning Celtic team. How is that happening?

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“Injury has affected that with Griffiths and Dembele having had spells out but even at that, it still shouldn’t be happening. I just think for this club you want the big guys, up in those forward positions, to score at least 15 to 20 goals.”

With the prospect of a double-treble still lying seductively on the horizon, people probably won’t care who gets the goals as long as somebody pops up as a match winner.

As Celtic aim to make it 10 games unbeaten against their old city rivals, Bonner doesn’t expect that particular sequence to come to an end on Sunday, even though the current cup holders have not be firing on all cylinders of late.

“It definitely gets harder for them (Rangers) the longer this goes on,” he said. “The question is, though, will Celtic play on the day? They’ve not been playing well recently. I think they’ll win it, though ... but I wouldn’t say any differently.”

Pat Bonner was speaking at a William Hill event. William Hill is the proud sponsor of the Scottish Cup