Dr Brennan, 59, the association's director of further education development, will bring a wealth of experience to the job. With a background in the civil service and local authorities, he has had more than 30 years' experience in education and has been the principal architect of FE policy since 1995, when he joined the AoC's predecessor, the Association for Colleges.
After postgraduate studies in quantum physics and a brief stint as a teacher, he joined the then Department of Education and Science and worked on establishing the new polytechnic sector.
He moved to Wiltshire LEA as assistant director for FE and spent most of the next 20 years developing the sector. He worked briefly for the South Thames Training and Enterprise Council.
He is chair of New College, Swindon, and a governor of Salisbury College, and is a regular contributor to FE Focus.
"He has no public presence," said one principal. "But he is hugely respected."
"He is very good behind closed doors," said another. "He is persuasive and always has the evidence to back up his views. But he is not a bruiser."
"He is the arch-technocrat and has all the facts and figures at his fingertips," said one civil servant. "A safe pair of hands."
Mr Brennan, who will take up the post in September, on a package of circa pound;120,000, said he would bring a considerable depth of knowledge and experience at managerial, governance and representative levels.
He said: "The Government has set us its agendas and there is a massive amount to be done. I think I can articulate the issues and where the underlying difficulties will lie."
Paul Mackney, chief executive of Natfhe, the lecturers' union, said he looked forward to Dr Brennan joining him in solving the historic problems of pay and workload.
Dr Brennan was at a meeting of the "workforce data working group" when the announcement was made. He rang his office, only to be told by answer phone that it had been evacuated. It hadn't been; they were just telling staff the news.