In the example below, the low number 35 is singled out as being worthy of note. But is it really that remarkable? The Rifle Brigade, alone of all the infantry regiments, did not start a new number series in 1881 but continued merrily along its way with its existing series. And why shouldn't it have done so? It was unaffected by Cardwell's changes and there was really no need to start afresh. It was numbering in the 4000s by July 1881, reached 9999 in 1889 and started a new number series in February that year. It reached 9999 for a second time in late 1903 and started again from 1 either very late 1903 or on the 1st or 2nd January 1904.
So in the case above, the number 35 does not signal that the man was an original member of a particular battalion (or regiment). He simply happened to enlist at a time when the Rifle Brigade had just started a new number series commencing from 1.
This man was a regular, career soldier, and as a general rule, the majority of Territorial Force units did start numbering from 1 when the TF came into being in 1908. In the same way, the majority of Special Reserve units did not start numbering from 1 when they replaced the militia in 1908. So low TF numbers might indeed signal early entry into a particular unit (and often prior service in the Volunteer Force). However, there are significant exceptions to the rule in both cases, some of which I have unpicked, and continue to unpick, on my army service numbers blog.
Images courtesy of the London Medal Company.