Hi
1851 census HO107 176 folio 514
3 Free School Lane St Edward, Cambridge, Cambridgeshire
Charles Todd abt 1827 Astronomer at Cambridge Observatory Islington
Charles birth was registered with Dr William's Library - so the family were non-conformist
http://www.bmdregisters.co.uk/The singing line: tracking the Australian adventures of my intrepid Victorian ancestors by Alice Thomson
'Todd was born on 7th July 1826 in Islington, the second son of a Welshman named Griffith Todd and his wife Mary Parker. Griffith was a melancholy figure who despite being a Dissenter drank to forget his problems.....' which according to the census (1851 - 1871) is not accurate as far as the actual birthplace of Griffith is concerned.
Griffith's second marriage confirms his father's name as George
5 July 1863 St John at Hackney
Griffith Todd Full Age Widower Accountant Paradise Place George Todd Stockbroker
Maria Stebbins Full Age Spinster Paradise Place Charles Stebbins Dyer
Maria Stebbins made her mark
Witnesses Mary Stebbings and Esau Stebbings his mark
If you have the dates 1760-1825 for George Todd then you must know at least where he died to know his age at burial and therefore his approximate birth year?
If he was a broker there are records for London brokers. However Griffith's brother Richard was a tailor (married Louisa Parker at the same church as brother Griffith, who was a witness to his marriage) which makes it a little less likely their father was a stockbroker, unless he was a much less successful broker.
Not sure what you mean for a family of such standing? Certainly Charles' family onwards. There as yet doesn't seem sufficient evidence to be sure Griffith's background was necessarily of 'such standing'.
Knights are generally armigerous (bearing a coat of arms). One source states in 1893 Charles Todd became a made K.C.M.G (order of St Michael and St George). In which case you might expect that the College of Arrms might have researched his family tree at the time.
http://www.college-of-arms.gov.uk/Regards
Valda