MI5 - Security Service

Staff and Management


The Security Service currently employs around 3,800 people. 41% of staff are women, 56% are less than 40 years old, 8% are from black or ethnic minority backgrounds and 3% have a disability.

Around 330 staff currently work in the Service on secondment or attachment from other departments and agencies.

The main investigative, assessment, policy and management work is carried out by generalist staff, who account for about two-thirds of the total. A comprehensive range of specialists in languages, technology, surveillance, IT, communications, protective security, administration, building services and catering support the work of generalist staff.

Our size and structure have altered considerably in recent years and will continue to do so to reflect changing threats, new working methods, available resources and the implementation of new information technology (IT). For example, we are currently expanding to reflect the greater volume of work undertaken in our international counter-terrorist sections.

For details on job opportunities in the Security Service, please see Careers.


The Security Service is headed by a Director General, currently Jonathan Evans.

The role of the Director General was set out in the Security Service Act 1989 opens in a new window. He is personally responsible for:

  • the operations and efficiency of the Service;
  • making an annual report on our work to the Home Secretary and the Prime Minister;
  • ensuring that we are politically impartial; and
  • ensuring that we obtain and disclose information only in accordance with our statutory responsibilities. We also disclose information for the purpose of the prevention or detection of serious crime, or for the purpose of any criminal proceedings.

In discharging these responsibilities, the Director General is assisted by internal mechanisms designed to ensure that our work abides by the principles that:

  • the rule of law is paramount; and
  • methods of investigation must be proportionate to the threat and their use properly authorised.

See the Organisation page for more information on how the Director General fits into the Service's organisational structure

Mr. Evans is the sixteenth Director General to have headed the Service since the post was created in 1909 - see Former Directors General for a list of his predecessors.

Key points

  • Around 3,800 people work for the Security Service.
  • 41% of staff are women, 56% are under the age of 40.
  • 8% of staff are from black and ethnic minority backgrounds, 3% have a disability.
  • Headed by Director General Jonathan Evans.

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