The unit consists of both uniformed and non-uniformed officers who provide close protection and guard Prime Ministerial residences.
This was highlighted when Prime Minister S W R D Bandaranaike was assassinated at his private residence by Talduwe Somarama.
The need for specialized independent unit was once again highlighted when personal from the internal security detail of the Royal Ceylon Navy, the Provost Branch were brought to guard Temple Trees on the night of 27 January 1962 when the attempted military coup by senior police and military officers was due to be launched.
This reduced the power of the post, however with the escalation of political associations as a result of the Sri Lankan civil war and the JVP Uprising (1988-1989) the security of the Prime Minister increased.
On January 5, 2000, personal of the PMSD prevented an assassination attempt by a female suicide bomber of the LTTE, the bomber detonated the bomb outside the Prime Minister's Office killing 13 civilians and three police officers attached to the PMSD.