Checking the QSA Medal Roll for the Norfolk Regiment, Drummer Sawyer was detached from the Norfolk Regiment and serving with the Norfolk Company of the 21st battalion Divisional Mounted Infantry (he had no connection with the Norfolk Co of the 7th Battalion MI), so it’s not even possible to certainly identify the original battalion of the Norfolk Regiment he actually belonged to before his detachment.
What is clear is his record, at least not discharged from the Norfolk Regiment, doesn’t appear to be in the WO 97 Soldiers Discharge papers at the National Archives, Kew (now available online but not on Ancestry).
A blogspot site that erroneously calls itself “British Army Services Numbers 1881-1918” [army service numbers weren’t introduced until 1920] identifies all the Regimental numbers found in the WO 363 (Burnt Documents) and WO 364 (Pensions) files in the National Archives; those records have now been digitised and are available on Ancestry. The blogspot identifies two surviving records for Norfolk Regiment soldiers of interest:
Record for No 3168 who joined on 13th March 1892
Record for No 3580 who joined on 9th February 1893
According to the blogspot, records of men between those numbers (Drummer Sawyer’s being 3499) don’t exist within WWI soldiers service or pension records; that means they either:
1] Served through into WWI and their records were destroyed in the WWII bombing and they didn’t claim a pension until after 1920;
2] Or were discharged before 1913 and didn’t serve in WWI, in which case their record should be in document series WO 97;
3] Or were discharged before 1913 and re-enlisted for WWI in another regiment so their Norfolk’s Regimental Number wouldn’t have been used in WWI;
4] Or were discharged dead (died in service), so no record was kept.
I don’t know of any records like regimental casualty returns (list of ineffectives, dead, discharged, sick, deserted, transferred etc.) that exist for the post 1881 period that would enable you to at least identify how and when he was discharged and I know Muster Lists and Pay Books don’t exist for the post 1879 period. So as far as any record of his service with the Norfolk’s goes, it look like nothing will be available.
All I can say is at enlistment a recruit into the regular army would typically be a minimum of 17yrs and maximum of 25yrs old. Taking the two enlistment dates above that would put Drummer Sawyer’s year of birth between 1867 (1892-25) and 1876 (1893-17), in other words 1871 +/- 4yrs.
Soldiers enlisted for a 12yrs short service enlistment of 7 yrs with the Colours (regular army) and were then discharged to civilian life, serving the last 5 years in the Army Reserve; so it’s possible he had actually been discharged before the Boer War and was a recalled reservist; a fair proportion of Boer War soldiers were reservists of one sort or another.
Also a soldier could serve any portion of his 12yrs enlistment with the Colours with the balance with the reserves or he serve to whole 12yrs and even re-enlist for 2nd 12yrs, but many of those would serve less than 20yrs in total.
Being between 41-49 in 1916, even if he served a full 20yrs and been discharged from the army before WWI, he would still be young enough to enlist in something like the Royal Defence Corps or Labour Corps for WWI. The problem then is that even if he served in one of those Corps in WWI there may not be a Medal Index Card for him if he didn’t serve abroad.
I’ve tried to give you a complete picture so that you may find something of use.