SINCE Brendan Rodgers arrived at Celtic, he has, for the vast majority of that time, been more than genial in his interactions with the press. He has been polite and classy in his conduct, so I won’t criticise him too sharply for his rather prickly demeanour last week. But there was clearly something eating at the Celtic manager, over and above my usual inane questions.

Was it the speculation surrounding Moussa Dembele? Perhaps. Or maybe he had gotten wind of the SFA’s plans to haul the majority of his starting 11 over the Atlantic for a spot of o joga bonita when they were supposed to be recharging their batteries on a sunlounger somewhere. Entirely plausible.

But then, he revealed that January window signing Marvin Compper would be out for four weeks through injury, and suddenly the sound of straws making contact with camels' backs was loud and clear.

It is bad enough that Compper, at 32, was the sole January window signing to that point that was still actually at the club. Lewis Morgan, of course, having been loaned back to St Mirren.

It was a further annoyance that Compper can’t play in European competition this season, where his experience may actually prove valuable to the Celtic backline. Now he was injured too?

If this was the reason for Rodgers’ unusually brusque manner, then it is hard to blame him. The signing of Compper, in my view, didn’t make much sense in the first instance. There is no sell-on value, of course, and while he may go on and be an asset for Celtic in next season’s Champions League, their defence could really be using some reinforcement before they take on Zenit in the Europa League this term.

Kristoffer Ajer is promising, but young and raw, and he was caught on the ball a few times in the midweek win over Partick Thistle. It will be a big call to throw him in against the likes of Russia star Aleksandr Kokorin. Dedryck Boyata is solid enough defensively without being comfortable on the ball, and while Jozo Simunovic is the best defender at the club, his fitness remains a real concern.

And was a signing like Compper really required solely for the domestic game? Even with the failings of the defenders I have listed above, their skillset is more than adequate to deliver Celtic a second consecutive treble, with the League Cup and the Premiership title already in the bag once more.

Now is the time for the Celtic board to step up to the plate and give Rodgers a rebate on the many millions of pounds he has poured into the club coffers by qualifying for the Champions League two years on the bounce, and deliver a real quality signing. Not a prospect. Not a veteran. But a player in his prime who can not only instantly improve this Celtic side, and rather freshen it up in the process, but excite the supporters too.

A marquee signing would also send out a real statement of intent that Celtic are in no mood to relinquish their dominance of the domestic scene. Make no mistake, confidence is quietly building on the south side of the city that Rangers may just be able to provide a keener challenge to Celtic for the title next season, even though their own signings in January have been modest in terms of what Celtic could afford to spend.

It is often said that it is when you are on top, that investment should be made to assert your superiority, and such is Celtic’s financial muscle compared to their rivals, they have a real chance here to stretch that gap further and secure it for years to come.

Given the standards that Rodgers lives by, and runs his squad by, it is safe to assume that he wants to continue the improvement of his side. It is unfair that he should have to do that with one hand tied behind his back due to any short-sightedness in the boardroom.

The Celtic manager said this week that he expects a signing before the window closes on Wednesday, and it will be interesting to see what the club can pull off. And equally, how much longer Brendan Rodgers will be able to keep his cool should the ambitions of his board not match his own.