It's only 17,702 records, but what records!
"This collection contains records of Canadians who fought in British Imperial services (navy, army or air) instead of the Canadian Expeditionary Force during WWI and received payments (gratuities) after the war was over. Recipients had lived in Canada before the war and returned there afterward. The payments were equal to what the soldier would have received as a member of the CEF and depended on rank, length of service, etc.It should be emphasized that these records relate to those who served in the British forces so will be of particular interest owing to the destruction of First World War British military records during the Second World War.
Documents typically provide name, residence/address, year of registration, beneficiary, rank, and unit. The listing of a beneficiary is particularly helpful because this may be a spouse or next of kin."
One record I looked at, for John Campbell Wright Reid included correspondence from the 1960s including the date of his death in the USA.
The records originate at Library and Archives Canada.