IF we learned anything from the Old Firm game on Sunday, it is that two men are going to have to put their hands deep into their pockets this summer. It was already well known that Dave King and his cohorts would have to stump up millions to take Rangers to the next stage.

With the team having reached the money-spinning William Hill Scottish Cup final, they may have to contribute a bit less from their own bank accounts, but they will most certainly have to invest in the squad, not least because Kenny Miller is 36 and several players are on short-term contracts that end in the summer. As soon as the transfer window opens, we will see if King has the money he says he has. For if Rangers are to get back to the top of Scottish football’s two-club pyramid, they will have to beat Celtic regularly, and lest anyone forget, league matches don’t have extra time or penalties.

Not a few Celtic fans will have been unpleasantly surprised to find that Rangers, on their day, are a very good football team. Yes, they have weaknesses (which Celtic failed to penetrate), but they do try to play attacking, passing football and when their confidence is high, as it was at Hampden, they are a match and more for Celtic or any other Premiership team – let’s not forget they beat Kilmarnock and Dundee in the previous two rounds.

As a consequence of Rangers’ undoubted improvement and the equally undoubted decline of the current Celtic team, the other man who will require to pony up this summer is Dermot Desmond. Not that he has to put in the cash himself – he just needs to say to Peter Lawwell: “Spend £15-£20 million and we’ll get the money back in the long run.”

As the major shareholder at Celtic, be in no doubt that Desmond has the call on the money that goes in and out of the famed Parkhead biscuit tin. Peter Lawwell may do the actual hiring and firing, but it’s the Irish billionaire who makes the monetary calls. As a fan himself, he also knows what the supporters are thinking, and no manager of an Old Firm side can survive losing the stands – the dressing room occasionally, but never the stands.

That’s why Desmond must bite the bullet and at least consider the future of Ronny Deila as manager. I never call for anyone to be sacked – except the political editors and correspondents of the Unionist media whose lack of integrity and professionalism is beyond forgiving – and I tend to follow the lead of Neil Lennon who said on Sunday that it is disrespectful to talk about a person in such a way.

Having known Neil quite a few years now, I know those feelings are genuine, and no, I have no insight as to whether he would return to Celtic Park, if asked.

The pity about Ronny Deila is that he is a nice fellow and an intelligent person. If he was a grumpy old goat and thick as mince, he would have lost his job by now for certain for failing to meet his own target of a domestic treble, something that Celtic should achieve given their vast resources in comparison with the rest of Scottish football.

Make no mistake, had Deila not been hand picked by Lawwell, Sunday’s defeat would have seen him on the first plane back to Norway. His tactics were as wrong as they have been so often before – not for nothing do some fans call him Ronny Duller. Playing with just Leigh Griffiths up front is not the Celtic way; their fans demand attacking, entertaining football and Deila is too wedded to his safety system.

His team selection was wrong, too. Erik Sviatchenko should have been on from the start, Kris Commons should have played at some stage, and just when Celtic needed youth, pace and flair, James Forrest has been frozen out because of his contract stance. He’s good enough for the Scotland squad but not the Celtic bench? Come on …

The players must take a lot of responsibility for the defeat to Rangers, but, in fairness, Scott Brown is clearly knackered, having played 39 games despite being out injured for the best part of two months. Mikael Lustig is only just less so after 46 games, and Nir Bitton is clearly feeling his 45-game season.

That is an indication of Deila failing to rotate the squad properly which is huge aspect of man-management these days. He has also stuck by the likes of Stefan Johansen when clearly his fellow Norwegian has been out of form for months. These are all indicators as to why Deila might not be up to the task of taking Celtic forward.

Indeed, Celtic fans are asking should Deila go now or at the end of the season? Sacked when top of the league – who would dare do that? You only need a lesson from Old Firm history to see how it can happen. In 1967, Scot Symon was sacked by Rangers chairman John Lawrence for the simple reason he wasn’t Jock Stein.

Symon’s Rangers were top of the league and had reached the European Cup-Winners’ Cup final that year, but Lawrence could see that the 56-year-old Symon would never match the feats of the decade-younger and more energetic Stein and disgracefully sent an accountant round to send

Symon packing.

Symon’s assistant, Davie White, took over at the age of just 35 and didn’t win a trophy in two years before he, too, was sacked when Rangers were sitting second top and ahead of Celtic.

The exit door was opened for White after Rangers lost home and away to Gornik Zabrze in the second round of the Cup-Winners’ Cup. The Polish side went on to make the final.

So there are historical precedents in Scottish football for going out at the top. Presuming Celtic will win the title, Desmond and Lawwell must ask themselves if Deila is the man to turn things round to meet the threat of Rangers.

For, as Sunday proved, that is a very real threat indeed and Celtic’s squad needs a complete overhaul.