In the 1901 Irish census they were aged 19,8,6 &4 years old respectively.
In the 1911 Irish census John & Jim do not appear,so it's reasonable to assume that in 1911, aged 29 and 18, they may well already have been in Australia. Are there any Australian records online that I should check for further information or clarification in or around these dates ?
I believe Nat ( Nathaniel) followed his brothers to Australia in 1914.
Bob's full name was Robert William Barclay - born 1897 (+ or - 1 year)
John Barclay was born in October 1881
Jim's full name was James Samuel Barclay - born 1893 (+ or - 1 year)