Neil Lennon conceded after this defeat that he had been aware of the need for a Celtic rebuild for some time. The comprehensive nature of Rangers’ victory merely emphasised this point to the wider world.

Lennon, whose position as the Celtic manager is secure only until the season ends, was rightly scathing of his players. “We were poor, very poor,” he said. “We lacked energy, desire and quality. The hungrier team won and that’s the biggest criticism I can level at the players. We looked flat. We looked as if we were fulfilling a fixture and that’s not good enough.”

Old Firm matches, even supposedly meaningless ones, tend to have broad ramifications. That Celtic were swept aside so easily will have resonated with the club’s directors, who must clarify Lennon’s position sooner rather than later. He cannot be fully exempt from criticism after a display such as this but he is unfortunate to have inherited a team who were limping towards an eighth title in succession.

Pointedly, Lennon highlighted a “lack of depth in the squad” which manifested itself here. Two key players, Kieran Tierney and James Forrest, missed this game through injury. Mikael Lustig departed with a hamstring injury that renders him a doubt for the Scottish Cup final. A side who so frequently peaked under Brendan Rodgers are reaching the end of their cycle.

Celtic’s need for surgery is of no concern to Steven Gerrard. The Rangers manager is due credit for his role in the narrowing of the gap between the clubs. This marked a second home success over Celtic of the season. Not so long ago, they were accustomed to harrowing times against their oldest foes.

“At our best, we have shown we can compete and beat them,” he said. “But we have to do it over a longer period of time and that’s a bigger challenge.

“You have to do it in cup competitions when it comes down to a one-off game. So that’s the challenge moving forward: can we be better over a longer period, can we be more consistent over a longer period? If it gets to the stage where we meet them in a cup competition, can we perform at that level? Because that level beats them.”

Apparently no Glasgow derby can take place without an element of controversy. Jon Flanagan was lucky to escape a red card after throwing an elbow at Scott Brown as Celtic prepared to take a second-half corner. Gerrard claimed not to have seen the incident but Lennon, while careful to distinguish the point from his anger at Celtic’s performance, did not hold back. “It was a clear elbow into the face,” he said. “It was totally unacceptable and unacceptable for the referee not to give a red card.”

Curiously the referee, Kevin Clancy, booked Flanagan, which suggested he had seen the incident. “It wouldn’t have changed the game,” Brown said. “We didn’t deserve to win.”

Long before this 51st-minute episode, Rangers were ahead. Only 109 seconds in, James Tavernier whipped a free-kick into the Celtic net. Lennon’s men were particularly disjointed in that early spell, with matters improving only marginally thereafter.

Scott Arfield, the best player on display, afforded the scoreline a fair complexion after meeting Glen Kamara’s pass. Jermain Defoe, lucky to escape a yellow card after a ludicrous piece of simulation in the first half, had produced a clever dummy before Arfield pounced.

Oliver Burke, whose clueless general display again raised questions regarding why he has commanded close to £30m in transfer fees, came closest to Celtic salvation with a late shot that Wes Foderingham batted away. The chance barely registered in the stands as the Rangers support celebrated; regularly in sectarian fashion, which Scotland’s football authorities give the impression they care little about with constant inaction.

More uplifting was the vigour of Rangers’ performance. Celtic did not come close to matching it; if alarm bells were not already ringing in high office, they should be now.