In 1851 Michael Spooner the tailor said he was unmarried.
Have you got his death certificate? If so, who was the informant.
If Edgar Spooner is 38, 58, 68 on the 1851,71,81 census returns, that suggests a birth year around 1813. There is an "Edgar", not a common name then, baptized 4 April 1813, St Botolph Bishopsgate. Absolutely no other details, says went away without being registered.
He later used the name King. Whatever the reason, could that have been his mother's name? Perhaps she wasn't married to his father, who presumably was Michael Spooner.
If Edgar's birth is proving elusive, what about his death, when was that?
John