The regiment was formed from 14th Intelligence Company known as "14 Int" of the Det (Detachment), a unit set up to gather intelligence covertly on terrorist suspects in Northern Ireland. Its recruits are trained by the SAS.

The level of involvement of the soldiers is unclear with it first being reported they were working purely in a surveillance role and then that they may have been on the bus following Mr De Menezes to the tube station.

To date the MOD has said the soldiers will be co-operating with the Independent Police Complaints Commission (IPCC) investigation but it will be interesting to see how long this continues. If the IPCC probe into areas that the army do not want exposed then they could withdraw co-operation as has happened on occasion in Northern Ireland.

The direct deployment of soldiers on the ground in Britain is further evidence of the anti-terror tactics first deployed in Northern Ireland coming home. Army units like 14 Int have a murky past going back to the 1970s. Former army and MI6 operative Fred Holdroyd has told how surveillance units transformed into killer units operating beyond the law. These operations later led on to the collusive network built up with Loyalist paramilitaries to target leading Republicans for execution.

The army unit responsible for much of the collusion structure was the Force Research Unit. Belfast solicitor Pat Finucane was one of the victims of these completely lawless actions. As noted here before it is one of the enduring ironies that former Metropolitan Police Commissioner Sir John Stevens, who was sent to investigate the Finucane murder, finished up bringing shoot to kill back to the streets of London.

The very brief history of what happened as a result of these SAS assisted surveillance units being deployed in Northern Ireland offers a salutary lesson for Britain. Once the army become involved in policing matters – under the guise of preventing terrorism – the whole terrain changes. Maybe this was what Tony Blair meant when he glibly referred to the rules of the game changing regarding combatting terrorism.

The deployment of the SRR on the streets of London is a matter of real concern. The Northern Ireland experience shows what can happen if such operations are not properly controlled and monitored.

It is vital now that the IPCC inquiry unveils exactly what the soldiers were doing on the day that Mr de Menezes died. Beyond that there needs to be a debate in Parliament as to the extent and terms of engagement of the British army on the streets of London and other cities.

End military impunity from the law

It seems a good time with the British army being deployed on the streets of London to look at the laws under which they operate.

The Article 7 – End Impunity Campaign has just such a goal. The campaign has come out of the refusal of the Ministry of Defence to remove from the army the two soldiers who were convicted of the murder of Belfast teenager Peter McBride in 1992. After completing their sentences the two Scots guardsmen Mark Wright and James Fisher resumed their army careers going on to serve in Iraq and other parts of the world.

The campaign is based on Article 7 of the Universal Declaration of Human Rights that states that "All are equal before the law and are entitled without any discrimination to equal protection of the law." The campaigners argue that the victims of serious crimes such as murder, rape, and torture are not afforded equal protection of the law if the perpetrator is allowed to return to a position where they are responsible for protecting the public.

Given recent developments the Article 7 campaign would seem like one that it is in all of our interests to support.