Whilst not impossible, an 1897 dob for William would make him only 16/17 when Joseph was conceived
1921 has William as 39 y 11 m, which matches an 1881 birth date
The WWI records of William who married Margaret Jane Nicholson Elliott and had a child Joseph William in 1915 survive. this suggests his dob is 1884
I'd be tending to the earlier date of birth