The size of an asylum seeker’s genitals will help determine whether he is entitled to thousands of pounds worth of taxpayers’ money.

The extraordinary revelation came during a High Court row over the age of a teenager who arrived in the UK in the back of a lorry.

Judge Stephen Morris QC heard the youngster – named only as A but under the care of Croydon Council – says he was born in November 1992 and has just turned 16.

However the local authority say he is now 18.

The boy’s age is crucial, because if he is 16 he will be entitled to welfare payments because he is a vulnerable child.

It could also have an impact on how successful his claim for asylum will be.

Launching a judicial review challenge against a Croydon Council ruling that he was 18, lawyers for the legally aided youngster said that medical evidence supports his claim that he is 16.

Judge Morris was told that a doctor who examined A believed there was an 86 percent chance that he was under the age of 17.38, and a 68 percent chance he was under the age of 16.33.

The "very experienced" consultant paediatrician, who made the findings in June this year, said A was "most likely" to be just 14. However they were rejected by Croydon officials in October.

The paediatrician's findings were reached after an examination of A’s private parts, with his height, how deep his voice is and his hairiness also taken into account.

Barrister Christopher Buttler said A - who says he is an orphan - spends much of his time thinking about his late parents and his “fatalistic” attitude was typical of someone in their early teens.

Mr Buttler also rejected arguments that his weight suggested he was 18, observing that he is bigger than average because he can't cook and is reliant on fast food.

Realising the importance of the case, Judge Morris reserved his decision on A's judicial review challenge and did not indicate when he would give it.