Again from online material (family tree on a/try):
William Dalton served as a regular soldier for 12 years with the Kings Own Scottish Borderers in Britain before emigrating to Australia at the age of 30. The information on the Roll of Honour states that he served with the 22nd Battalion No 5963 Sergeant William Dalton, Coburg, Melbourne, Victoria. He was Killed in Action on 3rd October 1917 at Ypres. His next of kin is given as his wife, Isabella Dalton (Matheson), Dalchalm, Brora, Sutherland, Scotland. William Dalton born c.1883 Tockwith, Yorkshire married Isabella Matheson in 1909 in Edinburgh.
Second marriage date not included but Isabella Matheson went on to marry a Walter Alexander Ross (b.1892 in Evanton, Parish of Kiltearn, Ross-shire).
Possible 1891 entry for William Dalton in Tadcaster, Yorkshire (the Scottish marriage cert will let you properly confirm his parents' names if you need this):
John Dalton 35, brewery labourer
Jane Simpson Dalton 34
George E Dalton 12
Amos Dalton 11
William Dalton 8 b. Tockwith, Yorkshire
John Dalton 6
Jane Dalton 4
RG12/3881/30/2
Monica
Added: As you thought Tony:
... There is the possibility that her brother-in-law is also commemorated on the same memorial ‘If only I knew his name’.
DALTON, , William A , Regimental Sergeant Major , 22nd Bn Australian Imperial Force
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