My Granddad and Uncle were both in the 4th Btn Liverpool Kings Regt in WW1 they were both listed on the Liverpool Kings Regt Devereux Touchscreen Database in The Kings Regt Display area of the Museum of Liverpool Life at the Pier Head Liverpool.
You can access in remotely to see if a relative is listed on it.
http://www.liverpoolmuseums.org.uk/mol/visit/galleries/soldiers/research/kingsreg/index.aspx There are 10 Welsby's 5 with Initial W but only one WH 10912 presume yours.
But have to attend personally to key in your relative to see if more info held on the database. In My case the Administrator of the Database had details of all the Census records my Granddad had appeared on. His Occupation, Wife Children. MM Gazette award and Newspaper date that his Obituary appeared in during 1943 I was able to send them a Photo to add onto the database.
They had similar info on my Uncle but no photo.
You never know another relative may have supplied one of yours ?
There may also be Regt Photos on this site where people add personal stories if their Relatives :_
http://www.merseyside-at-war.org/?s=4th+btnThe 4th Btn was stationed at Seaforth Barracks Litherland, Bootle and there are several photos of this suite :-
http://www.litherland-digital.co.uk/There are also several Genies that have old Group Kings Regts soldier photos on request posted on this site :-
http://www.bootlehistory.co.uk/forum/viewforum.php?f=10