The Home Office's own figures indicate just how much the 'child' refugee status is being abused.
I would be interested to see where the Home Office has stated that they have 'clear documentary proof' of age. Perhaps you could provide a link Howard?
The Home Office gives instructions on both how Children's Asylum Claims should be processed
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/537010/Processing-children_s-asylum-claims-v1.pdf
And also on assessing age
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/257462/assessing-age.pdf
You must remember that the function of a bureaucracy is not solve a problem but to clear files so that there is no longer any record of the problem.
A classic example of this with the Home Office is the Asylum backlog
http://www.express.co.uk/news/uk/694255/Home-Office-Visa-asylum-application-backlog-DECADES-records
which is not apparently newsworthy just now.
In spite of the best efforts of the workers at the Augean Stable that is Lunar House to get rid of the files (including dumping a load of old ones at the bottom of the lift shaft!) somehow the press found out about the backlog.
Since most of the punters were not eligible for 'asylum' and no-one was able to remove the little buggers 'Exceptional Leave to Remain' was invented since it meant a file could be closed and the problem ignored for five years until they came back for revocation of conditions and indefinite leave to remain.
Getting back to the 'bungle in the jungle' it is the job of the boys and girls at Calais to eradicate the 'problem' and if this means accepting a Red Cross document for example, where someone from that organisation, has accepted stated age and nationality, without any questioning, whilst dealing with a queue from here to eternity on some Greek island then whoopee, we have 'clear documentary proof' and the queue moves on!
Matters are also not helped with the fact that with the formation of Border Farce, highly trained Immigration Officers, most of whom started their shift by finishing the Telegraph crossword over coffee , were stuffed into polyester uniforms and subsumed into a union with the grunts who looked for extra cigarettes in people's baggage, whose start to the day consisted of checking their horoscope in the Sun 'newspaper'!
Most of the IO's at that point took early retirement and/or grabbed their index linked pension pot and went off to do other stuff!
'If no one went no faster than what I do there'd be a sight less trouble in this world'