Under the current law, naturalisation is normally only possible after 5 years’ residence in the UK or designated service (3 years if married to a British citizen on date of application).
In addition, the applicant must have been physically present in the UK on a day exactly 5 years before the date of application (3 years if married to a British citizen). The absence from the UK might have been for a few days a business trip to Paris or Dublin.
This means that members of British armed forces who apply under the 5-year route may be prevented by their absence from the UK 5 (or 3) years before the date of application, even where that absence was due to UK military service overseas. This is a demanding requirement for a serviceman, who will often have no choice as to where his is stationed.
This position has now been remediated in a new Act which passed with cross-party support in March. The Act will come into force from 13th May 2014. The Act allows the Home Secretary a discretion to ignore an absence at the start of the 5-year (or 3 year) period leading up to the naturalisation application, where the applicant is or was a member of the armed forces.
Absence should normally be overlooked if the person was outside the UK on military duty. Many Southern Africans have joined the British Army after 2000 and will have one less barrier to acquiring British citizenship.