It differs from the UK's intelligence agencies (MI6, GCHQ and MI5) in that it is an integral part of a government department – the Ministry of Defence (MoD) – rather than a stand-alone organisation.

The maintenance of the ability to give timely strategic warning of politico-military and scientific and technical developments with the potential to affect UK interests is a vital part of the process.

[4] The Committee of Imperial Defence, established in 1902, had the task of co-ordinating the different armed services on issues of military strategy intelligence assessments and estimates.

[6] Shortly after the 1945 end of the Second World War, the topographical department of the War Office was transformed into the Joint Intelligence Bureau (JIB), and its director, Sir Kenneth Strong, became a full member of the Joint Intelligence Committee (JIC) in January 1947.

[9] Although the DIS focussed initially on Cold War issues, more recently its attention has moved to support for overseas operations, to weapons of mass destruction and to international counter-terrorism activities.

Dr Brian Jones, head of the counter-proliferation analysis branch with others complained in writing to the then DCDI (Tony Cragg) that the wording of the dossier was too strong.

A particular source of criticism was a claim that Iraq "could" launch chemical or biological weapons within 45 minutes of an order to do so, should have been hedged with caveats.

[12] Another eminent weapons expert who worked closely with the DIS, Dr David Kelly, following off-the-record briefings to journalists about his criticisms of the "45 minute" claim, describing it as risible, were broadcast on the BBCs Today by Andrew Gilligan.

Jones has subsequently said that it was unlikely that should anyone with WMD expertise had seen the "compartmentalized" report prior to its inclusion in the dossier they would have supported its credibility.

The JSSO is based at RAF Digby in Lincolnshire under the command of a Group Captain with some 1,600 staff drawn from all three services.

These intelligence assessments draw upon classified information provided by GCHQ, SIS, the Security Service, Allied intelligence services and military collection assets, in addition to diplomatic reporting and a wide range of publicly available or ‘open source’ information such as media reporting and the internet.

[10] Support to contingency planning for operations: DI provides intelligence data and all source assessments that assist in preparations for future situations with the potential to require the commitment of UK Armed Forces.

These products, which cover political and military developments, country and cultural information, critical infrastructure and internal security, all aid contingency planning.

The assessments are distributed to decision-makers throughout the MOD, the Armed Forces, other government departments, allies, and UK Embassies and High Commissions.