Preston

If you are certain that the Robert PRESTON who went to America in 1924 was your grandmother's brother then it might well be helpful to contact the Archivist at Canford School to see if they have any more information.  There is a web site for the school here with a link to an email address - But of course this might be another Robert PRESTON. The school had been founded in 1923.

There is a christening on Ancestry for Robert Edward PRESTON who was born 5th Oct 1906 and christened 25th Oct 1906 s/o Samuel William & Caroline PRESTON at St Saviour's Croydon.

The death of a Robert Edward PRESTON was registered in Croydon in 1990 - (birth given as 5th Oct 1906)

FreeBMD does have a marriage in Croydon in 1960 of a Robert E PRESTON with a Dorothy M MARSH.  The marriage certificate should confirm his father's name and whether he had been married before.  There is also the death of a Dorothy May PRESTON in 1974 in Croydon.