Many thanks Trish. His father William Richardson moved to Cork, Ireland, in 1860 and died there in 1869. His mother may have died before then. This might be her (as she was baptised Elizabeth Bunker 11 June 1798, Wembury, Devon): Mary Richardson, aged 54, of Knackers-Knowle in the Parish of Egg-Buckland was buried 19 June 1853.
William George Richardson's sisters, Mary Simpson and Ann Eades, were with their respective husbands in 1861.
It is possible that William George Richardson may have gone to Ireland with is father in 1860, but I have found no record of that.
I do not have a birth certificate for William George Richardson. His parents William Richardson and Elizabeth Bunker were married 15 July 1819 in East Stonehouse, Devon. William George Richardson was with his parents in Plymouth in the 1841 and 1851 census, but I cannot find him after that.
This information from you is new to me:
Birth Regs;
RICHARDSON, WILLIAM GEORGE mmn BUNKER
GRO Reference: 1839 M Quarter in PLYMOUTH Volume 09 Page 415
RICHARDSON, WILLIAM GEORGE mmn BUNKER
GRO Reference: 1841 M Quarter in PLYMOUTH Volume 09 Page 410
Death Reg;
RICHARDSON, WILLIAM GEORGE age 0
GRO Reference: 1839 M Quarter in PLYMOUTH Volume 09 Page 263
It seems then that the first William George Richardson died and that they named their next son after him.