Thank you for your quick response.
In the 1891 census his wife Catherine (Kate) was shown living with a George Marshall, same surname perhaps related? George was also on 1901 census with her. George was also written as father for his daughters when they were married.
My very elderly father says there were a number of Marshalls in the area of London he lived in near his Grandmother, so no guarantee they were related.Robert was born in Amberley, Surrey and George in Soho, London.
The last child, and they were all close in age,born to Robert and Catherine was born in 1886. There were no children born to George and Catherine.Catherine I believe was born in 1843, Robert 1837 and George 1850. So I think that Robert went into an institution around 1887/1888. There is, as far as I can see no marriage between George and Catherine.