The Tyneside ground was jammed to its 36,000 capacity for Beardsley's benefit match in which Celtic beat Peter Beardsley Select 3-1. And, while the Toon Army duly honoured the local lad who became one of Newcastle United's all-time greats, they worshipped Keegan with Messianic devotion.
Chants of "Keegan! Keegan!" boomed round the ground as Fulham's chief operating officer took the field to replace Paul Gascoigne for the final 20 minutes. He failed to hit the target, but the decibel count hit the roof as the Toon Army celebrated the cavalier days of old.
It was only to be expected. It was, after all, the first time Keegan had returned to St James' since the breakdown of his Newcastle United dream two years and three weeks ago.
Having led Newcastle from the clutches of the old Third Division to the brink of the Premiership title, he left because of the club's imminent stock market flotation. "Once the football became of secondary importance I had no interest in staying," he said.
And Newcastle United have not been the same since, as the Toon Army were lamenting last night. Still awaiting the arrival of sexy soccer, Ruud- style, they were given a tantalising glimpse of the fantasy football of old.
The dream team assembled around Beardsley included colleagues from the beloved cavalier side that Keegan built - Andy Cole, Alan Shearer, and Steve Watson - and from the Newcastle team in which he played alongside Keegan in the 1980s, Chris Waddle and Paul Gascoigne.
Beardsley's squad also included, ironically, Kenny Dalglish and Paul Dalglish, both of whom happen to be at odds with the present regime at St James' Park.
Dalglish Snr is in dispute with his former employers over the terms of his departure five months ago. And Dalglish Jnr has become the focal point for dissension within the ranks of Ruud Gullit's squad, the senior members having taken exception to his sudden disappearance from the first-team picture.
For Dalglish Snr there was also the chance to take on, if not take over, the club in whose colours he became Beardsley's boyhood hero.
And green and white was almost as prominent as black and white, the travelling Celts having literally brought Newcastle to a halt when draping an Irish tricolour across the Tyne Bridge en route to St James' Park.
They made their presence noisily felt inside the ground too, jeering Gascoigne's every touch, chanting Beardsley's name and celebrating as though their team was about to win some kind of British title after a Darren Peacock own goal, a Lubomir Moravcik piledriver and an 86th-minute tap-in by Mark Burchill emphasised their superiority on a carnival night.
The Dalglishs made a joint entrance midway through the second-half, but the third Newcastle manager in attendance merely waved to the crowd at half-time.
Gullit happens to be suffering from flu, as well as a bad side, and in the latter regard his recovery will not have been helped by confirmation from Milan that Taribo West will not be moving to Tyneside.
For Beardsley, who scored with a twice-taken penalty two minutes from time, it will be back to the Third Division basement on Saturday with Hartlepool at Rochdale - from the spotlight to Spotland. For Keegan, it will be back to the Second Division promotion trail with a home game for Fulham against Northampton.
"I'm pleased that tonight has given me a chance to say goodbye to the Toon Army," he said. "It closes a chapter in my life in the nicest possible way because the Newcastle supporters are fantastic people."Reuse content