[1] Over the next few years Junior football continued to grow in popularity, and the new competition had to be regularly expanded to accommodate a rapidly increasing number of clubs.

Petersham became entrenched at the top level and contested every First Junior competition from 1886 to 1895, winning it in 1889 and making the semi-finals on four other occasions.

During this period the club also boasted an impressive role of Junior representative players and supplied a steady stream of quality footballers to the Senior competition.

Petersham, who had been suffering from a drain of quality players to the Senior competition anyway, was a more significant and probably unintended casualty of this policy.

The Kentwell Cup had been presented to the winners of this competition for the first time the previous year, and so began Petersham's long association with that coveted trophy.

At this time the New South Wales Rugby Union was looking fill a vacancy in the District competition, and so dominant were the Petersham and Roseville clubs that it was decided whichever of them won the Kentwell Cup in 1935 should be promoted forthwith.

[1] After the Second World War, Petersham came under the patronage of the famous and mercurial Ron McLean, a veritable legend of Subbies rugby.

The feat has been repeated on numerous occasions since, and the various touring sides have boasted many prominent New South Wales and Australian representative players.

Petersham entered the 1st Division, and in 1972 made the Kentwell Cup grand final for the third time, only to lose it to Hunters Hill.

At the end of 1974 however, an internal dispute saw many of the dual premiership players leave the club, and within two years Petersham had dropped to 3rd Division.

The period had its highlights, in particular the establishment of a highly successful U21 Colts team, but overall the club failed to live up to expectations.

The adventure ultimately came to an end in 2005 after a disastrous run of injuries and plain old bad luck finally took its toll and saw Petersham relegated back to 3rd Division.

The multitude of off-field events celebrating the club's historic milestone was manifested with success on field with all four grades showcasing in the 3rd division grand finals in poor weather conditions in Sydney.

This strip was eventually overshadowed by the Myrtle Green of Randwick however, and so when Petersham joined the newly formed New South Wales Rugby Union Non-District Competition in 1929, the colours were changed to the modern "Sky Blue and Maroon, 4 in.