Have looked on National archives site, no luck today, system playing up I think,
I found the first child of Edward and Bessie, there was an Albert Edward Ralph born 8.11.1903 died 1906.
(not unusual to have mothers maiden name added with first child).
I think it is possible that Clarence joined R.N. and could have transferred to Merchant Navy, which might explain the long age gap before he married. He might have been known as Edward Clarence as well.
His father Edward was also a sailor.
Maurice may have joined the R.A.F. Suggest you look for the parents on the 1921 and 1939 census, in case they moved out of Plymouth.