Any boy or teenager who is the age of 17 and six months was classed as a adult soldier if they joined the Army. When the army got rid of the junior soldiers and junior leaders, in the early 2000s ( for the worst possible reasons), this meant that you could have 16-year-olds with men of 36 years of age, when you are training them to be soldiers, you soon realise both groups have different needs, the 16-year-olds were not allowed into the NAAFI without an escort as the NAAFI sold alcoholic drinks so you had to have them escorted there at different times. You then add the other problem,of the older soldiers coming back in to the accommodation who had been drinking?
Also, when you discipline a 16-year-old soldier in comparison to a soldier who was over 18, You can soon understand the problems you would have, every other day you are dealing with the parents of 16-year-olds asking about how is little Johnny is getting on, and can you put him on the phone, As they wished to speak to their little baby, the Labour Party ( in Government at the time) and the MOD soon realised they had made a major mistake and reinvented junior soldiers and junior leaders, by coming up with the junior Apprentice College at Harrowgate in Yorkshire so reinventing the wheel.
I've posted the front covers from the Judge's service records, John the 96th of Foot at the age of 13 .In December 1863, his brother Alfred joined the 96th of Foot April 17, 1873, at the age of 14, both of their records should be on Find My Past as part of the war office (WO97) service records.
When John joined up 23rd of December 1862, his Rank was Boy, until July 1863 , when the Rank change to Drummer, in October 1865 . He then changed to the Rank of Private Soldier.
Alfred joined up April 1873, with the Rank of Boy Soldier, until April 1876, when he attended to the age of 15 years old, when he then changed his rank to a Private Soldier