Thanks guys.
I've got the marriage to Jannot Saunders in 1840, producing children Louisa Mary King Spooner (born & died 1841) and Mary Spooner (born 1842).
They are indeed the family in Green Street, St Andrew, Holborn in the 1841 Census HO107 Piece 670 Book/Folio 9/10 page 12
I've got Jannot Spooner dying in 1846 and the marriage to Elizabeth Escott in Clerkenwell in 1849.
I've got them in the 1851 census at 12 Boswell Court, Saint George the Martyr, Finsbury (HO107 Piece 1513 Folio 137 page 10)
I've got a son Thomas Escott Scott Spooner born in 1857
I've not got Elizabeth Spooner's death yet ... but I have Edgar Spooner marrying for a third time (under the name Edgar Spooner King) to Eliza Wright in Hackney in 1863.
It is not clear why he adopted the "King" in his name ... but it had been used as a middle name for his first daughter, of course; and his son Thomas Escott Scott Spooner also adopted it, but as a middle name not a final name (Thomas King Spooner) and all of his children had King as a final middle name (or possibly hyphenated it to King-Spooner).
I have three further children for Edgar and Eliza (Eve, born about 1867 and possibly the Evelyn F King born in 1866; Adam born in 1870 and John born in 1873).
I have Edgar King, wife Eliza and children Adam and Eve in the 1871 census at Artiller Lane, Bishopsgate (RG10 Piece 416 Folio 19 page 31).
I presume that Eliza died between 1873 and 1881 ... but there are FAR too many Eliza King deaths in London to try to whittle it down to the correct one.
I have Edgar's son Thomas King Spooner marrying on 2 April 1879, his father being identified on the marriage certificate as Edgar King, and his occupation given as Cutter.
Finally, in the 1881 census I have 68 year old widower Edgar King, a Tailor born in the City of London, living at 5 Fanshaw Street Shoreditch with his 8 year old son John King (RG11 Piece 394 Folio 113 page 56).
He's been an absolute NIGHTMARE to figure out ... but I'm nearly there now. All I'm missing is his baptism, his death, and a plausible explanation for the change from Spooner to King, with his son becoming King Spooner (and, doubtless, heaving a great sigh of relief as he dropped the Escott Scott). But ... as with everything else about him ... the baptism and death are proving elusive