Service number prefixes

Gents,

During my research into the 24th Regt, I have obviously compiled a large number of names and associated service numbers. Most will be aware that in general, the prefixes are 1-24/1234, 2-24/1234 to differentiate the Battalions and the Brigade 25B/1234 for post April 1873 followed by SWB/1234 when they changed title. The 2nd Battalion obviously started from scratch on formation in 1858 but the 1st Battalion appears to have allocated new numbers from about April 1857. What was, or would be the best way to show the difference between the allocations, just plain 24 ie 24/1234 for those enlisting pre April 1857?

As far as I am aware the only soldier pre 1857 who served long enough to be awarded the SAGS was 3732 Pte William Craddock with the 1877-1878 clasp.

Does anyone know if this new allocation was as a result of a General Order from the War Office?

Regards,

Bill