[7] Construction of the two-storeyed concrete building with multiple classrooms, an assembly hall, tuck shop and gardeners' quarters started in 1938.

[8][9][10] The school commenced on 15 January 1939[1] with twenty[11] students in two classes in the Volunteer Drill Hall[5][12] – construction of the new building was still in progress - at Jalan Hospital.

Headed by Mr Koe Ewe Teik and assisted by Inche Daud bin Mohamed Amin,[1][13] the intention was to pioneer a system of admitting 10-year-old boys who have already studied a few years in vernacular schools, to be promoted to Standard III or IV - according to each boy's ability - after two years.

Upon relocating back to the school building, extra-curricular activities in the form of games were organised for students - in parallel with the resurgence in sports participation in Kluang[14] - and a Wolf Cub Pack was established in 1947.

[17] The headmaster Mr. Koe Ewe Teik, who was a vice-president of the Badminton Association of Malaya, was appointed in 1948 as one of the selectors of the Malayan team that went on to win the inaugural Thomas Cup in February 1949.

Mr. C. D. Westwood was appointed headmaster on 1 May 1949[20][21] and at the end of the year, the first batch of fourteen students sat for the Senior Cambridge Examinations.

[5] A block of six new classrooms of timber construction - costing approximately $28,000[24] (Malayan dollar) - was added to the primary section in 1952.

In the late 1970s, the hall was partitioned into multiple classrooms using makeshift walls, and the quadrangles were utilised as the venue for school assemblies.

[25] To broaden the extra-curricular activities, a Red Cross Link was started with 24 members that year, and in 1955 the Cadet Corps with a platoon of 30 was begun.

New science laboratories were officially opened by the State Secretary, Che’ Abdul Rahman bin Musa in 1956.

[5] On 21 December 1963, the Malay classes were incorporated - foreshadowed in the Education Ministry's announcements[29][30] - into a new school, Sekolah Menengah Kebangsaan Kluang.

[31] Students who failed the Secondary Schools Entrance Examination (the local version of the British Eleven-plus) to qualify for entry into Form One had the option to enrol in a two-year course with a practical and vocational bias (e.g. carpentry and poultry-raising),[32][33] at the newly started Secondary Continuation School (Malay: Sekolah Pelajaran Lanjutan) at SES on 2 April 1962.

[5][34] The Secondary Schools Entrance Examination was scrapped in 1964, allowing for automatic promotion of Standard VI pupils to Form One in 1965.

[35] The secondary continuation school system was abolished at the end of 1964 and the students, following a scheme to bring them up to par, were admitted to SES in 1965.

[22] In September 1965, a total of 637 Forms One & Two pupils and 25 teachers were transferred to the newly established Lower Secondary English School (Malay: Sekolah Menengah Rendah Inggeris) – headed by Mr A Sellathuray[37] - at 3rd mile, Jalan Mersing, occupying seventeen classrooms.

To this end, fundraising projects were launched and when Tuan Sheikh Hussin Ali became headmaster, an outdoor sports complex alongside the field was added to the expansion plan.

[6] A fundraising walkathon was held on 4 April 1981, the proceeds of which went towards the building of three Science labs, an air-conditioned Reference library, a bus shelter and a roof over one of the basketball courts and spectator seating area at the sports complex.

The abbreviated school motto, ONWARD in argent (white) is on the gules (red) fess i.e. the band that runs horizontally across the shield.

In the late 1970s, the public secondary school uniform for boys (up to Form Five) was transitioned from an all-white attire to white shirt & olive green trousers.

[44] The school magazine ONWARD was first published in 1947, inspired by Mr. K. M. Mathai the guiding force behind the GES Literary and Debating Society.