During the 1939-45 war, day tutorial engineering work was done in conjunction with the Admiralty, but day release National Certificate (Engineering) did not start until 1949. City and Guild classes in Mechanical Craft, Fabrication of Steelwork, and Welding began in 1962 followed by pre-vocational and Motor Vehicle work in 1964. Management tuition was begun in 1968 and the Higher National Certificate classes in 1973. School link work was increased by the raising of the school leaving age in 1972. Process Plant courses for the Sugar Trade restarted in 1976 and work experience began in 1977. Teaching staff employed rose from eight in Session 1963/64 to twenty one in 1968/9 and to thirty four in 1976/77.
Up until the 1960’s the college was predominantly a male institution, catering as it did for the heavy industries. The economic conditions were changing however and the cyclical nature of employment in these areas as well as their gradual decline contributed to the expansion of training for young girls. Women were now looking for their own careers as well as jobs that could keep the family going in times of hardship.
The Department of Business Studies was set up in Session 1964/65 in the Holmscroft Annexes running pre-vocational secretarial classes and link classes for local schools. After this building was destroyed by fire, temporary accommodation was found in the Mearns Street School for some two months and then the department moved to the Eastern School in Gourock for the start of Session 1966/67.
After a year this was demolished for a housing re-development so classes were moved to temporary huts at the former Boom Defence Depot. From there it moved in Session 1968/69 to the Glenpark Annexe which was much more spacious, allowing classes to be run for the S.N.C.B.S. and Institute of Bankers, as well as Secretarial and Retail courses.
This was a period of quite rapid expansion and the Department soon outgrew its’ accommodation and had to obtain supplementary space in the old St. Columba's School.
In Session 1972/73 it moved to the new College and with the vast increase in space was able to expand the professional studies section into H.N.C. work and take on a large programme of TOPS work in the secretarial section. The custom built retail section was able to expand rapidly from this point, and all evening classes which had previously been offered by the Finnart Evening Centre were transferred to the College.
Catering courses were started in that first year in converted Home Economics premises on the 6th Floor, and later that year moved into a custom built suite on the 7th Floor.
That year Renfrewshire also began an expansion programme in pre-school education provision, and accordingly the need for more qualified nursery nurses became apparent. James Watt College was chosen as the training centre for Renfrewshire and both the Junior and Mature courses were started and housed within this department.
A Hairdressing salon, after some delay in recruitment of teachers, was then set up and equipped. By session 1978/79 the Department was fully utilizing all the available space at its disposal in the building.
Student Numbers in the first few years after the new building opened was some 530 full time equivalents.