This post will look at regimental numbering in the 3rd (Special Reserve) Battalion of the King's Own Yorkshire Light Infantry (KOYLI). Thanks to AHJ for planting the suggestion.
The Special Reserve was formed in 1908, replacing the militia. Serving militiamen were given the option to join the Special Reserve, remain as militiamen or take a free discharge. Men transferring to the militia were given a bounty of £2 rendering them liable for foreign service in a time of emergency. These men also retained their original militia numbers.
Thus, for example, Daniel Firth was given the number 9546 when he originally joined the 3rd (Militia) Battalion on the 25th June 1906. He opted to transfer to the 3rd (Special Reserve) Battalion in June 1908 and retained his old number, 9546. Men joining the 3rd (Special Reserve) Battalion for the first time were given new numbers beginning at 1 which were prefixed with the number 3/. This prefix was inconsistently used, as it was in other regiments, for that matter.
By March 1909 number 3/353 had been issued; 3/594 by February 1910, 3/727 by June 1911, 3/907 by March 1912, 3/1237 by July 1913, and 3/1369 by March 1914.
Recruitment into this battalion increased dramatically by August 1914 and so we see 3/1567 issued on the 15th August and 3/2149 issued on the 2nd September. By the end of the month, over a thousand men had joined the battalion with the number 3/3204 issued on the 26th September 1914.
The regimental number series continued to be used well into 1915. For instance, 3/3683 was issued on the 26th October 1915 and 3/3691 on the 20th November 1915. This is the highest number I have come across in this series although do beware other numbers masquerading as 3rd (Special Reserve) Battalion numbers.
For example, 18849 Harry Bennett joined the KOYLI on the 30th August 1914. This regimental number belonged to the series which had originally been the preserve of the two regular battalions. Harry was originally posted to the regimental depot on the 30th August and then to the 3rd Battalion on the 27th October 1914. His regimental number on his attestation papers includes the number 3/ prefix and yet this number does not belong to the 3rd Battalion series which, as noted above, may not have made it beyond 3/4000.
I research soldiers! Contact me if you need help with your military ancestor.