With the creation of the Special Reserve in 1908, the Devonshire Regiment effectively lost a battalion. Prior to this date, as well as its two regular battalions, it also fielded two militia battalions, the 3rd and 4th Battalions. Wiht the creation of the Special Reserv, the 4th Battalion was abandoned, men now being given the option to sign up to the 3rd (Special Reserve) Battalion. As far as regimental numbering in the battalion was concerned. Men who were still serving with the 3rd (Militia) Battalion simply joined the 3rd (Speical Reserve) Battalion with their old regimental numbers. 4th (Militia) Battalion men who now opted to join the 3rd (Special Reserve) Battalion were given new numbers from the 3rd Battalion series which was, itself, a continuation of the militia number series. There are many examples in surviving service records of serving militia men joining the Special Reserve in 1908 but only signing up for the unexpired portion of their militia service.
Men joining the militia and special/extra reserve were not career soldiers. They were men who had completed a period of training alongside career soldiers at the regimental depot but they then went back to their homes, turning out annually for drills and camp. Men of the Militia and the Special Reserve signed up for six years' service and knew, in the event of war, that they would be called upon to fill gaps in the regular battalions. A glance at most 1914 Star rolls will show plenty of evidence of Special Reserve men who served alongside career soldiers. Sometimes their numbers are prefixed by the number of their battalion - typically a 3/ or 4/ in most line infantry regiments - but just as often there will be no prefix.
The first 3rd (Special Reserve) Battalion number I have on my database - and there will be many earlier ones thatn this - is 4893 Samuel Rowe who was a time-expired soldier with 12 years' service under his belt. He was also a serving member of the 4th (Militia) battalion and when he joined the 3rd (Special Reserve) Battalion on the 27th June 1908 he only signed up for 2 years and 200 days which was the unexpired portion of his militia service. The new number he was issued with was from the series which had been in use for the 3rd (Militia) Battalion.
Here then, are some sample numbers for the 3rd (Special Reserve) Battalion, Devonshire Regiment: