Glad you found the marriage for them. Like you, I wonder why they married 100 miles away. Maybe they were on a "holiday" and decided on a whim to tie the knot away from family?
Quite possibly, I know so little about him that anything is a possibility at this point!
I've received the GRO for the below:
Name: Joseph Jones
Death Age: 73
Birth Date: abt 1847
Registration Date: Apr 1920
[May 1920]
[Jun 1920]
Registration Quarter: Apr-May-Jun
Registration District: Birmingham
Inferred County: Warwickshire
Volume: 6d
Page: 226
Joseph Jones
Male
73 Years
Formerly a Brass Caster
M. Jones widow of deceased present at death
18 Reservoir Avenue, Clark Street
Last address I had for him was the 1911 census, living with his son at 74 Fulham Rd, Sparkhill. Which appears to be around 4 miles from Clark Street.
No mention of him being a brass caster, the the previous two censuses he was a provisions merchant.
M. Jones is correct as we now know he married Martha.
So I'm not sure if this helps us, unless someone can dig or some more information.. or think of any other avenues of attack!