Soldier's service numbers

[LizzieL]

Is it possible to find out when a soldier joined up (roughly) based on their service number? All I can find for my grandfather is his medal card, which has no dates on at all. The only medals were the Victory and British. By Victory is written: RASC/101.B.144.14645, and by British it just says -do-
His record must have been one of the many lost ones.
He was Heber Eltham (pretty unique!) service number M2 200095 on his medal card. But on a letter from him to my great grandmother from France he quotes the number 20095.1 without the M2 prefix. So I guess he just missed one of the zeroes, but I don't know whether the ".1" after the number is significant.
He was a private in the Army Service Corps

[Ruskie]

If I remember correctly, I believe you can get an indication of when someone joined up from his service number.

Unfortunately I can't recall how to do this, but I am sure someone will know.

[Ruskie]

This doesn't help with dates, but you may find it interesting:
https://armyservicenumbers.blogspot.com/p/number-prefixes.html

There are other blogs on the site which may contain something useful.

[Jebber]

I can’t help with enlistment dates, but I believe  M2 denotes Army Service Corps Electricians.
MT On the postcard is Mechanical Transport.

[ShaunJ]

M2 is Mechanical Transport. See

https://www.longlongtrail.co.uk/soldiers/a-soldiers-life-1914-1918/letter-prefixes-to-british-soldiers-numbers-in-the-first-world-war/

and
https://www.greatwarforum.org/topic/274198-asc-number-prefixes-2019/

[ShaunJ]

Per the postcard he was with  20th Auxiliary Petrol Company, which was 590 MT company.

There's a mention of it here: https://books.google.co.uk/books?id=WN0mEAAAQBAJ&lpg=PT131&ots=m_1MopuiUS&dq=ASC%20%2220th%20auxiliary%20petrol%20company%22&pg=PT131#v=onepage&q=ASC%20%2220th%20auxiliary%20petrol%20company%22&f=false

[LizzieL]

Thank you all very much for the information. I have found a few solfiers with numbers very close to his
Bernard Arrowsmith M2/200093 joined up 6 Dec 1915
Robert Dingle M2/200098 joined up 20 Nov 1915
(dates seem the wrong way round for number sequence)
Herbert Drewitt M2/200096. Can't find any service record, but his medal card has exactly the same written on it as Heber's. Could they have enlisted together?
I can't find anything more on Herbert unfortunately. DOB could be quite a wide range
Heber was born 08 Dec 1884, (but not registered until Q1 1885), relatively old when he joined up.
Here is front of postcard. he is writing to his mother (my great grandmother) to say he got back safely and it is very hot in France. So at earliest likely to be summer of 1915. (My great grandfather died in October 1914). The picture looks like winter, he's wearing a coat and the other soldier on the right of picture without a coat looks a bit cold. There aren't any leaves on the trees but they could be dead. So I would guess the picture was taken some time before he actually wrote it.

[ShaunJ]

What a great photo!

[Ruskie]

What a great photo!

It is excellent.