The birth of Gadeside Rangers Football Club’s senior side happened ahead of the 2002-2003 season when the U17’s side - which had been together for a decade - took the step up from junior football into an adult league. Manager Andy Davies entered the side into the Olympian Sunday Football League and were placed into the second division. Gadeside’s first senior game was a cup match against premier division Headstone Athletic which the youthful Gadeside team narrowly lost on penalties. That first season saw the side originally struggle but enjoy a strong second half culminating in a 5-0 victory over Inter FC to secure promotion on the final day. Jay Evans won the players’ player of the year award.

The start of the 2003-2004 season saw a number of the regular player head off to university and as such several new faces arrived. It was to be a memorable season for Gadeside as they quickly found their feet in the first division and at Christmas, found themselves sat at the top of the table. A run of 7 consecutive victories in the New Year was ended by a narrow defeat to fellow promotion chasers PJJ Electrical while the club enjoyed success in the Hertfordshire Intermediate Cup with wins over strong sides from around the county. The most memorable of matches came against Albion Rovers as Gadeside won a thrilling tie on penalties. Gadeside had been leading 3-1 with minutes remaining, only to draw 3-3. Having gone behind early in extra-time, Gadeside restored parity late on before Tom Oliver and Jay Evans were the heroes in the shoot-out.

Gadeside continued to pick up points in the league as the season entered the final stages and secured the league title with a game to go following a 3-1 win over AFC Artichoke. The county cup dream came to an end against eventual winners Kcinsatop from Hitchin though Gadeside gave them a run for their money before eventually being beaten 3-0. Nevertheless, Gadeside had secured successive promotions to find themselves amongst the big boys. Jay Evans, who won the players’ player award for the second year in succession, had an excellent season in the heart of a defence which conceded 23 goals in 22 games. Toby Zhou finished top scorer with 17 goals.

The 2004-2005 season again started with a number of comings and goings as Gadeside prepared for life in the premier division. Inconsistency was the theme of the season as Gadeside were often bullied by teams but they still managed to pull off some fine results. They reached the semi-final of the Chairmans Cup, disappointingly losing 3-2 to Railway Club before a wretched end to the season saw them finish in 4th place. Jay Evans was again superb and completed his hat-trick of players’ player awards while Toby Zhou and Adam Hills were joint top scorers with 13.

With a number of players returning from university and the arrival of some exciting talents, Gadeside started the 2005-2006 season in bullish mood. Things began well as Gadeside picked up 13 points from 15 and enjoyed one of their finest hours as they smashed Watford Observer premier division side Hammer - who had won the Herts Sunday Senior Cup two years before - in the first round of the same competition. The excellent league form continued and Gadeside found themselves clear at Christmas, though their nearest rivals Woodside had games in hand. Success was also coming in the Presidents Cup as Gadeside swept to the semi-finals where they won a narrow game 3-2 over Riverside Royals to secure a place in the final.

The big game of the season saw the top two meet in a match Gadeside knew they must win to keep their title hopes alive. Having gone a goal down, Gadeside drew level and should have gone on to win, but a late goal against the run of play gave Woodside the win which all but ended Gadeside's title hopes for another season. The season did end of a high note as Tom Mitchell and Adam Hills bagged a brace each as Gadeside beat The Beaver 4-2 to allow club captain Danny Everritt to lift the Presidents Cup. Adam Hills with 22 and Tom Mitchell 21 were top scorers while Hills walked away with the players’ player award. It was a fitting end to the season for manager Andy Davies who announced his resignation as manager. Andy had been involved with the club for over 10 years and had been a tremendous servant.

Club chairman Darren Hufford took over at the helm as Gadeside began the 2006-2007 season looking to go one better than the previous year and win that elusive premier division tilte. Hufford's brief tenure was full of incident as Gadeside found themselves in trouble with the league over issues of playing unregistered players. Gadeside were originally docked 10 points, which was then reduced to 4 but not further despite an appeal to the committee. After an explosive game against Headstone Athletic – in which the game was abandoned – then restarted, a Headstone player was sent-off – then came back on – and Gadeside threw away a lead to lose in the final minutes, Hufford resigned. With no obvious choice to replace him, player Adam Hills offered to take over the reigns with the support of the players. Hills got off to a perfect start as Gadeside went on an 11 match winning run to find themselves top of the league and in two cup semi-finals. After comfortably beating North Bushey 4-1 to reach the Birkdale Trophy final, Gadeside were involved in a top-turvy match against The Reindeer in the Presidents Cup. Losing 3-1 going into the final minutes, Gadeside got back to 3-3 before a cruel deflected free-kick in the dying seconds sent the holders crashing out. The league form began to stutter and, along with the points deduction - it was clear that the first league title would have to wait. A 3-1 victory over The Reindeer saw Gadeside finish 3rd.

The final of the Birkdale Trophy was against Headstone Athletic who had already wrapped up the league with some ease. Gadeside enjoyed much of the first half and were left to rue a host of missed chances when Headstone took the lead. Adam Hills’ penalty brought the sides level just before half-time but three goals in a 5 minute spell from Headstone blew Gadeside away as they were left to lick the wounds of a frustrating season. Ian Freeman won the players' player award while Adam Hills was top scorer with 23 goals.