Short visits to the UK does not maintain ILR. You have been lucky. There are a number of things you will need to work out to see when you qualify for naturalisation. 1. The date when you apply - you must have been physically present in the UK on the corresponding date 5 years ago. 2. In the 5 years ...

I first went to the UK on Aug 2006 and got my ILR in Oct 2011 base on 5 years work permit. I am living outside the UK since I got my ILR. ILR is still valid since I went back the UK every two years. If I go back to stay for one year,when can I apply for naturalization?