Close but informal co-operation between the British and Irish governments over immigration controls in the 1960s was kept secret to avoid Irish embarrassment, according to a Home Office file released at the Public Record Office in London today.
As the number of immigrants entering Britain in 1964 increased, particularly from Commonwealth countries, the Labour government reviewed immigration controls.
The Home Office file, released as part of a programme of "open" government under New Labour, refers to the "Irish backdoor" and notes that Irish immigration controls prevented the "easy access" to the UK through Ireland of "people whom we would not normally admit to the UK direct".
It should not be made public, the file states, "that there is close, if informal co-operation between the respective immigration controls in preventing evasion: the Irish Government would be embarrassed if this became known or if there was any suggestion that the Irish Government were helping us to work our immigration controls".
Just as immigration controls were being reviewed, an anomaly was discovered between the treatment of Commonwealth and non-Commonwealth citizens. Even though Irish citizens formally ceased to be British subjects in 1948, they were still subject to the Commonwealth Immigrants Act, although in reality only the section relating to deportation was actually enforced.
There were no immigration controls between Ireland and the UK and Home Office officials were sensitive to criticism that under the legislation Commonwealth citizens were worse off than Irish citizens.
To get around the problem, Home Office officials considered a border control, along the Northern Ireland land Border with the Republic. However, it was decided this would be "impractical" and would only be employed as a "last resort".
Similarly, enforcing a control between the island of Ireland and Britain would be an imposition on British and Northern Irish citizens and was rejected. Supervision of Irish citizens in Britain, by monitoring labour permits, was also rejected by officials, who said: "There would be nothing to be said for a system of control that allowed Republican Irish to come here but hindered them from work."
Eventually, it was decided to bring Irish citizens "generally" under immigration controls, while acknowledging it was "not expedient" to operate border controls between the two islands.
"It would be a pity," the file says, "to disturb these convenient arrangements simply to meet the view that the special treatment of the Irish is proof of a `colour-bar' mentality on our part".