The wing, who racked up 62 tries in 148 appearances for Saints, charged forward in support of his All Stars team-mates, picked up the ball and dived over the line for a first-half try in his testimonial match.
It was what the crowd bathed in the Tetley’s Stand sun had come to see and the joy was etched on Diggin’s face.
And his smile grew even wider in the final seconds as he was handed the chance to score the final try of an entertaining afternoon.
While the result was unimportant - the Legends seemed to have the edge over the All Stars at the denouement - the overall occasion and the money raised for local causes, including Niamh’s Next Step, were not.
On a less serious note, there was a large comedy element to proceedings - and some equally sizeable players - with Lennie Newman, who called for fresh body parts after his early stint on the pitch, doing a lengthy routine on the PA system.
Saints mascot Bernie did his bit too, getting a slice of the action before being replaced by Academy coach Mark Hopley. It was a surreal moment.
There was the return to the Gardens of Kiwi full-back Bruce Reihana. He was lavished with chants of ‘Bruuuuuce’ by the adoring Saints faithful, who hunted in packs after the game as they sought to get the autograph of their long-time hero.
And there were plenty of other Northampton greats playing their part, with Budge Pountney pocketing a pair of tries and Allan Bateman battling hard.
But it was a day that was all about Diggin, who fought an ankle injury to ensure he could get on the pitch and milk the acclaim of the Gardens.
Some things never change - and memories of the true Saintsman’s playing career will continue to live long in the memory of everyone who witnessed it.
Saints All Stars: Bruce Reihana; Phil Robinson, Allan Bateman, Matt Allen, Matt Goode; Rory Teague, Johnny Howard; Tom Smith, Dan Richmond, Robbie Morris; Jon Phillips, Christian Short; Gavin Kendall, Budge Pountney, Mark Hopley.
Replacements: Sam Miller, PAUL DIGGIN, Dave Abrahams, Fen Gallagher, Chris Kirby, Mark Tucker, Ben Barwell.
Saints Legends: Alex Foster; Tom Foden, Chris Hyndman, Ed Binham, Richard Blank; Alex Rose, Ben Jones; Mark Kefford, Kyle Dufty, Ben Briddon; Johnny Chance, Lennie Newman; Charlie Smith, Darren Fox, Mark Soden.
Replacements: Liam Wilkinson, Andrew Phillips, Ben Mann, Chris Kirby, Joe Newman, Dougie Rafferty, George Newman.