It was the day when the club completed a memorable double, scooping their first Premiership title to add to the previous week's European Challenge Cup triumph.
And the man that made it all possible was one of the club's own: Alex Waller.
The Kettering-born prop, a graduate of the Northampton Academy, popped up in the final seconds of extra-time to seal a dramatic 24-20 win against Saracens at Twickenham.
Waller was hoisted high into the sky as celebrations started before Saints savoured the trophy lift in front of their ecstatic supporters.
Here, we look back at that incredible day with hero Waller.
Q: What was the build-up to the final like?
A: It was quite strange because the Challenge Cup win was a big thing in itself for the club. Any silverware is worth celebrating, but we had to put that on hold because we had the big prize coming up at the end. I don't mean to belittle the Challenge Cup, but the big one was the Premiership because the club had never won it before. We had the bitterness of the year previous to that (when Saints lost in the final to Leicester) and we wanted to go one better. It was a tough build-up emotionally because I was so excited. I was young and I'd never won a big trophy before. I'd been involved in that Heineken Cup final but I hadn't won a big trophy so it was massive for me personally. But then you had to park it because we had a game to play. The build-up was interesting and it was a mixed bag for me. I'd started the whole season and then I was benched for the two finals, which was frustrating. I was told at the time that I would be on the bench for the Challenge Cup final and then start the Prem final, but it didn't work out like that. There was some frustration for a day or two but then you've just got to park it and get on with the job - and it worked out all right in the end! In the hotel the night before the game we all got our shirts with the embroidery on for the game and it was just another away game at that point. We didn't want to get too worked up the night before the game so we just sat around with the lads, chilled out and had some food. The tension starts to build an hour before you go to the ground. You have a team meeting and do some flexibility work and you can see lads starting to focus. Headphones go on, music is on and there's not as much laughing and joking. There's still some because there's a long time before kick-off but lads like to prepare differently. Then walking into Twickenham was awesome because it was a sea of Saints fans. Obviously it was just because our bus was pulling up and the Sarries fans weren't that interested, but when we pulled up, all you could see was Northampton shirts and flags and face paint and you could hear the cheering. Getting off the bus and walking through the gates at Twickenham is always a special experience. It was a sea of green and then into the changing room to start work.
Q: What was said in the changing room before the game?
A: The disappointment from the year before was clearly still fresh in everyone's memory. The way we worked things back then was that just before the huddle, the bench and everyone else cleared the room before the final team talk so I'm sure Woody (Tom Wood) and Dows (Phil Dowson) had their bits to say but we were all outside at that point so I'm not so sure exactly what was said. But I imagine it was along the lines of taking the opportunity and sticking to our processes. We couldn't afford to get caught up in it all. Once the boys came out of the dressing room we gave them a little cheer and walked out, saw all the flames and pyros and then we were into it.
Q: How confident were you that you could win that game?
A: It was obviously our second time of being in the final in as many years and we probably weren't expected to get there in that first year. Everyone probably expected us to lose to Sarries away in that 2013 semi-final because of the season they had and we were the underdogs. But the following season we had gelled as a squad, made a few additions and built on the previous years. There was just an underlying confidence - not arrogance - that if we turned up on our day we could beat anyone. That group of boys was really close-knit and when we went out there, even when we went behind, calm heads prevailed. We knew we could come back at any point and win the game. It was two great teams and no one deserved to lose, but there has to be a loser and I'm just happy we were on the right end of it.
Q: You came on for Alex Corbisiero in the 54th minute. How desperate had you been to get on the field?
A: I was really desperate to get on. I had the disappointment of not being selected to start after having what I felt was a great season for me that year. It was my breakthrough season. Then to be let down at that end point was just the game of rugby - there's highs and there's lows. But once it's been announced there's nothing you can do about it and there's no point crying about it. You've got a job to do and the boys coming on at the end have got to finish the job, which is arguably as important as the boys starting. I've played in plenty of games where we've started strongly and not finished strongly meaning we've ended up losing. Once you've had a bit of a moment to yourself, it's just 'right, next job, crack on' and you've got to add your weight and make your mark on the game to do the boys proud when you come on. If you're moping you're going to let your team-mates down. It was one of the biggest games in the club's history so you want to be involved in it, but rugby is a 23-man game and you've got the same amount of say on the game as when you start. I was chomping at the bit. I was up and down, up and down and then Courtney (Lawes) managed to split me open when I came on as well so that was a quick sprint to the medic's room to throw some stitches in. I didn't want to mess around with anesthetic or anything like that. Then it was straight back on the pitch because I'd waited so long to be on and I'd had to come off for five minutes to get stitched up.
Q: It was an awful looking injury. How exactly did you do it?
A: Nowadays the HIA doctor would have probably taken me off for another 10 minutes to have a walk through a routine, but I was coherent and I can remember everything. I just tackled Jackson Wray and it was at the same time as Courts. We both swung round and his head clocked me straight in the cheekbone and split me open pretty good. I think I probably had a little fracture because it was pretty sore. I remember after I was hit - I didn't know it was Courts at the time - I tried to open my eyes and all I could see was blood on my arm and I thought I should just lay there for a second to see what was happening. I was probably a bit rude to the medical staff at the time, just wanting to get back on. Kiera Ruddy, one of our physios, was in with me in the medical room and I was talking and spitting blood everywhere. She was like 'can you just calm down a minute?' and the doctor did a great job because I haven't even got a scar any more. I was wanting to get out as quickly as possible. You would think having stitches with no anesthetic sounds pretty miserable but when you're in the heat of the moment and adrenaline is pumping you don't really feel it. But when we came off and had the celebration the doctor said we'd have to do it all again because the stitches weren't really fit for purpose.
Q: So, you got back on and you scored what proved to be the winning try after the TMO confirmed it. Did you always think you'd scored it?
A: I always knew I had scored it. The worry for me was that I knew it was on the line and not clear over and there was a lot of bodies around. Jamie George was one of the boys who jumped down to stop the try and you're like 'did he block the camera?'. It only takes a knee to be in the wrong place and then it's a different story. I could see the line. I burrowed under a few bodies and just thought I'd stretch out. I wasn't fully aware the clock had gone. I thought we still had time for Stevie (Myler) or one of the lads to call it back and maybe go for a drop goal or another attempt, but all's well that ends well.
Q: What were the celebrations like on and off the field?
A: Everyone was going mental and Tom Mercey actually came over while I was hugging Ross McMillan and he just rubbed my face as a well done. Obviously I had six stitches under my eye and he managed to put his fist right in the cut. There was Champagne everywhere and it turns out Champagne and open wounds stings, but it was only shortlived so I wasn't too fussed by that. It was one of the best environments I've been involved in and especially after the disappointments of the previous year. There was lots of songs, lots of beer, lots of Champagne. I wouldn't have wanted to go into the changing room afterwards because there was Champagne all over the ceiling. It's one of my favourite memories that I've been involved in.