Notes:

George Henry Frost, husband of Amelia Dudley's niece Louisa Hunt, lived in Plainfield, New Jersey, He and his wife visited Robert Dudley at least once; George also bought paintings from Dudley and corresponded with him for many years.

George and Louisa's son Edwin Hunt Frost and daughter-in-law Marguerite Scribner Frost corresponded with Robert Dudley in 1909 and with Ambrose and Guildford Dudley in the 1920s and 30s. They lived in Yonkers, New York, and visited England on at least one occasion.

Frank Hall Childs, who lived in California, had met Ambrose in 1931, and corresponded with him in 1934 after Guildford's death. Guildford had also mentioned Childs in a June 1933 letter to Edwin Hunt Frost. Childs was married to a niece of Robert Dudley's wife Amelia, also named Amelia (Hunt); she was the aunt of Edwin and Harwood Hunt Frost.
Frank Childs wrote an article on Robert Dudley and the Atlantic Cable which was published in Telephone & Telegraph Age, August 1st 1933; a shorter version appeared later that month in the California newspaper The Palisadian. The articles included a transcript of a previously unknown letter written by Robert Dudley to Sophia Hunt in 1866 at the conclusion of the Atlantic cable expedition in September that year.
Childs also wrote a history of the Hunt family in 1934 (unpublished).

Harwood Hunt Frost (Edwin Hunt Frost's brother and Frank Childs' nephew by marriage) responded to the article with a letter to Childs which was published in the January 1st 1934 of Telephone & Telegraph Age. He mentioned meeting Robert Dudley and hearing stories of laying the Atlantic cable, and also noted that:
“Guildford was engaged in telegraph work for some years also, having lived for some years on the east coast of Africa, in the employ of the Eastern Telegraph Company, and is now a pensioner of that company. My brother, Edwin Hunt Frost, 27 Morsemere Place, Yonkers, N.Y., has among his various treasures a set of the pictures of the laying of the Atlantic cable.”
Guildford had died at about the time this letter was written.

Violet Hunt is mentioned in letters from Guildford Dudley to Edwin Hunt Frost.

Robert Dudley census records:

No record for Robert or his family in 1841 census.

1851 [30 March]:  Robert C Dudley, 25 is a lodger @ 95 Stanhope Street, St Pancras.  He gives his birth place as Hackney and his profession as architect.

1861 [7 April]: 32 Sussex Place Kensington
[This appears to be the couple's first home after Robert's marriage to Amelia Hunt in August 1859]
Robert 35, Artist in Painting, born in Hackney
Amy 27, Wife, born in Liverpool
Guildford 7mths, born in Kensington

1871 [2 April]: 31 Lansdowne Road, Notting Hill
Robert 45, Artist, born in Hackney
Annie 27, Wife, born in Liverpool (should be Amelia or Amy)
Guildford 10, Scholar, born in Kensington
Robert A 4, born in Kensington (this would suggest that Robert was born in
Sussex Place circa 1867; an April 1868 letter from Robert Dudley to Henry Clifford has the Kensington address)

1881 [3 April]: 31 Lansdowne Road, Notting Hill
Robert C 55, artist, born in London
Amy 46, Wife, born in Liverpool

1891 [5 April]: 31 Lansdowne Road, Notting Hill
Robert C 65,  Artist in Painting & Design, born in Clapton
Amy 58, Wife born in Liverpool
Guildford 30, Electrician, born in Kensington
Robert A 24, Student in Art, born in Kensington

1901 [1 April]: 31 Lansdowne Road, Notting Hill
Robert C 75, Artist Sculptor, born in Hackney
Amy 67, Wife, born in Liverpool
Guildford 40, Electrician, born in Kensington
Robert A, Artist Sculptor, born in Kensington

1921 [19 June]: 31 Lansdowne Road, Kensington
Amelia 88y 2m, Head, born in Liverpool
Guildford 60y 9m, Retired, born in Kensington
Robert Ambrose 54y 5m, Artist, born in Kensington