Hi George
My Clements all come from this area right back to 1800's l will try to give run down as l think you have my William brother to James and John we was missing him this may be him.
John William Clements was the second son of James Clements and Mary-ann Holliday.
Other children were James Henry b1910 Joseph 1916 and Edward 1923.
The father James was born in East Ham in 1888 brothers were John and William (this may be the one) (family are listed on church of later day saints family search.org.)
Parents to these were John and Mary Clements (maiden name unknown at present). This John Clements was the second son of John Clements and Mary Bland (she came from Glandour Ireland) this goes back to 1832 roughly. Best Wishes Sue.