By far the largest, and oldest component of Conservative Central Office (CCO), was the Organisation Department, which dated back to 1911. The Organisation Department was responsible for the state of readiness of the Party organisation throughout the country. In addition to the staff based at CCO in London, there were 11 area offices corresponding to the Provincial Areas of the National Union, each office being staffed by a Central Office Agent (otherwise known as the Area Agent), with deputies, available to advise the constituencies.

The Organisation Department was something of an umbrella body, acquiring responsibility for agents, Conservative trade unionists, local government, speakers, education, the Overseas Bureau, Young Conservatives, students, personnel, the Small Business Bureau, and legal affairs, as the work of Central Office expanded. At various times these sections have been elevated to the status of Department reflecting changes in emphasis within the Party, but then later reintegrated back into the Organisation Department; for instance, the short-lived Community Affairs Department, which existed under its own director from 1975 until 1980.

The Organisation Department came under the direct responsibility of the Principal Agent (from 1930, known as the General Director). Following a review of the Party organisation undertaken by Deputy Party Chairman Lord Stanley in 1927, the Principal Agent was assisted in this by a deputy, known as the Chief Organisation Officer. Following the abolition of the post of General Director in 1966, this post was re-named Director of Organisation. Ultimately, one of the Party's vice-chairmen, appointed by the Party Leader, has responsibility for the Party organisation.

In common with all areas of the Party's headquarters' organisation, the Organisation Department has seen many changes over the course of its existence. Between 1980-1985, it was known as the Organisation and Community Affairs Department. From 1985-1989 it was known as the Campaigning and Training Department, and since 1989 it has been known as the Campaigning Department.

Principal Agents/General Directors, 1868-1966:

Chief Organisation Officers/Directors of Organisation/Campaigning: