Did not find children, but would not rule it out.
There was a Robert Macgregor who was in WWI.
United Kingdom, World War I Service Records
||Glasgow, Lanarkshire, Scotland|
||Highland Light Infantry|
||12th (Service) Battalion|
|Birth Year (Estimated)
||Govan, Lanarkshire, Scotland|
CITING THIS RECORD
"United Kingdom, World War I Service Records, 1914-1920," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:QVBL-XJP4 : 23 March 2015), Robert Macgregor, 1914; citing Glasgow, Lanarkshire, Scotland, Highland Light Infantry, regiment #18634, publication WO 363, The National Archives, Kew, Surrey; FHL microfilm 7,280,601.
Sometimes a cemetery record will show names of children, but I don't know the name of the cemetery after he died in Brampton.