The stylish midfielder, now 20, joined the club aged six, signed professional forms in July, 2014 and just four months later, made his first-team debut against Partizan in the Europa League.
Now he's put pen to paper on a new deal with the club until 2019.
He's almost reached the top of the ladder, but now the toughest task of all - becoming a first-team regular in the Premier League and following in the footsteps of Harry Kane, Ryan Mason, Tom Carroll and many more...
"I’ve definitely progressed and I feel I’ve come a long way since the start of the season," said Harry. "I’ve learned a lot from the manager, from the players and everyone around the club.
"I’m really enjoying my time, loving it. I just want to take that next step now and that’s to play a few more minutes and generally kick on."
Harry's views on potentially taking part in our huge Europa League Round of 16 tie against Borussia Dortmund sums up his thought process.
"It would be lovely but I have to focus on one little step at a time and the next step is to hopefully make it into the squad, the next step after that is to then get onto the bench and then, hopefully, get out there," he said. "I just take step by step and fingers crossed I’ll get there."
How does it feel to sig a new deal until 2019?
Harry: "I’m delighted. I’ll just continue focusing on my football, try to kick on and try to get into the squad. I train every day with the players, I do exactly the same programme as them and I’m on the same schedule. Naturally, I’d love more minutes but I do believe the training and the hard work I’m putting in means I’m playing my part every day."
Below: Harry in action against Fiorentina
What has it been like to be around the squad this season?
Harry: "As a young player, it’s everything you want. You want to be around top players and a top club and a team that’s pushing for the top honours. It’s a fantastic club to be involved with especially at such a young age."
Mauricio Pochettino certainly puts his faith in young players...
Harry: "The manager trusts young players and on a personal level, I’m grateful for the chance he’s given me. From my point of view, I now have to repay that faith by playing well and when I get the opportunity, to make sure I take it."
Finally, are you happy with your game at the moment?
Harry: "Yes, I’m happy with what I’ve achieved so far, obviously I need to put that work into practice in games now and prove it on the pitch."