Sullivan is a keen Tweeter and was obviously in nostalgic mood when he took to the social networking site to reveal 'one of his favourite days at West Ham' was the Championship Play-Off final win over Blackpool in 2012.
One of my best days at West Ham! pic.twitter.com/Hsl81vbsmy— Jack Sullivan (@jsullivanwhu) September 7, 2015
The youngster has been with the East Londoners since January 2010 when his businessman dad David and David Gold took over the debt-ridden club.
While the result of the play-off final, which West Ham won 2-1 in the dying moments thanks to a Ricardo Vaz Te strike, is something that will live long in the memory of fans it was not the best performance a Hammers side has ever produced.
The euphoria which greeted the final whistle was more down to the fact the club desperately needed to bounce back to the Premier League at the first attempt after relegation the season before under the hapless Avram Grant.
But it nevertheless gave the club's loyal supporters a memorable day out at Wembley where they got to see their team lift some silverware of sorts.
What is West Ham's finest hour in history?
It may mark young Jack's finest day in his five years at the club, but what ranks at West Ham's finest moment of all time?
Here we have highlighted some of the major moments in West Ham's history and we want you to have the final say.
First FA Cup win vs Preston North End in 1964
The Hammers first truly established themselves in 1964, when manager Ron Greenwood guided the club to their first major trophy in the shape of an FA Cup final victory over Preston North End. Ronnie Boyce scored a last minute goal in a famous 3-2 win with striker Johnny Sissons becoming the youngest ever scorer in a cup final.
European Cup Winners Cup win 1965
The success of 1964 was repeated a year later, this time with an unforgettable run in Europe which culminated in a 2-0 European Cup Winners Cup triumph over 1860 Munich at Wembley. It was a game graced by the club's greatest ever son Bobby Moore producing what then manager Ron Greenwood described as "Bobby Moore's greatest game. Technical perfection."
World Cup win 1966
Moore, along with club teammates Geoff Hurst and Martin Peters, was lifting silverware at Wembley again a year later, this time with his country. The Three Lions skipper led the Hammers trio to England's only ever World Cup victory over Germany 4-2 with Hurst scoring a hat-trick and Peters getting the other in what has become known as the year West Ham won the World Cup.
Second FA Cup win vs Fulham 1975
West Ham won 2–0, with the two goals scored by Alan Taylor. But the game will perhaps forever be remembered in the history books as the last time a club fielded an all-English team to win the FA Cup.
Third FA Cup win vs Arsenal 1980
The Hammers' last major trophy and one of their most significant too. They beat Arsenal by a single goal, scored by Trevor Brooking. But crucially to date, a statistic unlikely to change any time soon if ever, it is the last time a team from outside the top flight has won the FA Cup.
Best ever top flight finish of third in 1986
The 1985–1986 season saw manager John Lyall lead West Ham United to their highest ever top flight finish, coming a close third behind Liverpool and Everton. They won 26 of their 42 games and finished with 84 points, two behind Everton and four behind eventual double winners Liverpool. The Hammers team of 1985-86 became known as The Boys of 86 and is the closest the club has ever come to a top division title.
Championship Play-Off Final win vs Preston 2005
The 2005 Football League Championship play-off Final was contested by West Ham United and Preston North End at The Millennium Stadium, Cardiff. West Ham won 1–0, with a goal from Bobby Zamora which secured Alan Pardew's side's return to the Premier League at the second time of asking. While the club were relegated again six years later, it gave them the platform to reach the 2006 FA Cup final, play in Europe and sign players like Carlos Tevez and Javier Mascherano.
FA Cup Final defeat vs Liverpool 2006
Yes the game, won by Liverpool on penalties after a 3-3 draw over 120 minutes, brings back some painful memories for West Ham fans. They thought they were going to watch their team lift the cup again until Steven Gerrard scored THAT goal in the dying moments. But the match has been voted as the best ever FA Cup final and West Ham played a major part in that. Steven Gerrard called West Ham and their fans "special" in his autobiography after that game for their conduct, which fans will say is the true 'West Ham Way'.
Championship Play-Off Final win vs Blackpool 2012
That brings us up to young Jack's favourite day at West Ham, the 2-1 win over Blackpool in 2012 which sealed a crucial return to the top flight for the debt-saddled Hammers. Carlton Cole and Vaz Te got the all-important goals as Kevin Nolan led Sam Allardyce's side to a famous Wembley win. It has given the club the foundation to establish themselves once again as a top flight force and secure a big move to the 54,000 Olympic Stadium from next summer.