Over 5,000 supporters flocked to Franklin's Gardens to enjoy some sun, fun and plenty of rugby, with the prop scoring the clinching try as his South Sea Islanders pipped a Saints team 67-65.
Tonga'uiha received a standing ovation after the game - something which mirrored that which preceded the action in memory of Niamh Curry, a five-year-old who sadly lost her battle with neuroblastoma last week - and then conceded he was staggered by the amount of support he received on the day itself.
"I was very surprised," he said. "On Friday we had only sold 3,200 tickets, so to get it up to five thousand and to see all the fans in the ground made me a bit emotional and speechless. It was very, very humbling and was very much appreciated.
"I didn't think the day was going to turn out as well as it did, to be honest. Fair play to the likes of Alesana Tuilagi for turning out the day after playing at Twickenham, and the weather held out, which was good considering the amount of rain we've had in the past few weeks and months!
"We've tried to make the testimonial family oriented. I've got four children of my own and we've tried to get the kids and their parents involved and the family day showed what we've been wanting to do."
For all the information about Soane Tonga'uiha's testimonial year, including the charities and causes which are being supported by the Tongan international, visit www.soanetongauiha.com