Service Numbers

Hello researchers.
Is it possible to link a service number to an individual? I have three possible service numbers that may relate to my Uncle James Smith "De Sevia" who was a TSM in Troop 3 of number 1 Commando. The numbers are:
6844557
3970799
T/195982
I would appreciate any help you could give me.
Regards
Steven Smith

Reference your uncle: https://www.commandoveterans.org/JamesSmith1Commando

The answer is yes but principally on official Service Records which are not available online. Additionally it is if they have received an award, or officer promotion or commission, or or something meriting inclusion in the London Gazettes or War Office / other files. Or if they have been mentioned in a Unit War Diary , or were a casualty, ie. killed, wounded, missing, or prisoner of war. Finally some regimental personnel cards or records are now available online. I personally cannot find anything on those numbers but I do not have access to everything. The numbers you gave were in batches issued to the following Regiments/Corps.

6844557 - King's Royal Rifle Corps.
3970799 - Welch Regiment
T/195982 - Royal Army Service Corps.

The first service number is for a chap called Hales, there are no WO records for the other two, on the third either with or without the T/ prefix. It might be worth checking the image for his cap badge it may be Welch Regt.
Hope this is of some use.