Just so you know, you have Indefinite Leave to Remain, not enter.
If they have been here for 16 years, it probably is Indefinite Leave to Enter.
Before the new immigration rules came in in July 2012, people who had been married to and living with a UK citizen outside the UK for at least 4 years, could apply directly for ILE from outside the UK as long as they had taken the Life in the UK test first (which could be taken as a visitor).
If they hadn’t passed the test, they would be granted a 27-month spousal visa with KOL Required so that they could immediately apply for ILR as soon as they had passed the test after arriving in the UK.
Sadly, both options were stopped with the new rules in July 2012.
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