Hello Sandie,
Hopefully you will find attached two transcripts of Newspaper reports of 8 January 1915. Please excuse any spelling mistakes etc as it was converted digitally to a word document.
Kentish Mercury.doc (Size: 22.5 KB / Downloads: 487)
Gazette.doc (Size: 25 KB / Downloads: 541)
Note one and of the articles gives his name as 'John' and his wife's name as 'Eva', living at 25 Nelson Street, Harrow-on-the-Hill
An Arthur James PRIOR married a Mary Eva GATES between Oct-Dec 1904 at Hendon, Middlesex reference Vol: 3a Page: 456.
This couple with 3 children appear on the 1911 census at this website http://www.1911census.co.uk/ which has a pay-as-you-go option.
From the 1911 census you should be able to confirm they are the correct couple and what follows and in an email is correct.
Arthur James PRIOR
Birth: 1884 Jan-Mar, Berkhampstead Vol: 3a Page: 572
Christening: 8 Mar 1884, Tring, Hertfordshire
Born: 22 Dec 1883 Father: James Mother: Sarah
Source: British Isles Vital Records Index
In 1901 Arthur appears to have left home and is working at the "Rose and Crown", Tring, Hertfordshire as a Stable Lad/Groom.
Aged 8 the 1891 Census shows Arthur with his parents John, a General Labourer and Sarah in Tring along with a sister Annie aged 5 and James mother Anne.
I haven't been able to confirm his parents wedding but a James Prior married a Sarah KEMPSTER or BOSHAN in 1883 Oct-Nov at Berkhampstead, Reference Vol: 3a Page: 775.
I have found details of Arthur's wife's family, in addition there may be relatives of your friend in Canada who have further details which I will forward to you in an email.
Finally, try the local library where they lived as it may have the widow's story?