Hi,
The official Gazette dates for Sydney's WW1 DCM and MM are as follows.
The DCM
The London Gazette, published date 30th August 1918, Supplement 30879, page 10264.
10264, Supplement to the London Gazette, 3rd September 1918.
70119, CPL S.H. Archbold, Tank Corps, (W Ealing)
The MM
The London Gazette, published 28th January 1919, Supplement 31150, page 1449.
Supplement to the London Gazette, 29th January 1919, 1449.
70119, Lance CPL Sidney Herbert Archbold, DCM, 5th Tank Battalion, Tank Corps, (West Ealing. W)
Because the DCM is a conspicuous award one down from the VC for non officers there was a citation added to the Gazette Notice, I can copy this out if you wish or you could go to the LG site and download both notices, search under he service number, 70119 it makes it easier because he is in as
SIDNEY Herbert Archbold for the MM and S. H. Archbold for the DCM.
https://www.thegazette.co.uk/ Gerry