Patsy,
This looks to be your family in 1911. Benjamin and Rachael had been married 6 years. They had had 3 children and one had died.
http://www.census.nationalarchives.ie/pages/1911/Armagh/Loughgall/Castleraw/327519/
Rachael in 1901 when still single:
http://www.census.nationalarchives.ie/pages/1901/Armagh/Loughgall/Castleraw/1015836/
Her marriage in 1905:
https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1905/10160/5696481.pdf
Benjamin in 1901 living in Kincon. So he appears to have moved to Castleraw after marriage:
http://www.census.nationalarchives.ie/pages/1901/Armagh/Loughgall/Kincon/1015861/
Children to the 1905 marriage:
Gerald 27.1.1907
Benjamin 10.2.1910 died 23.2.1910
William 27.2.1911
John 7.7.1915
Moses 4.12.1917
Margaret 21.2.1919.
Rachel appears to have died in 1919 judging by this probate abstract:
Williamson Rachel of Castleraw county Armagh married woman died 23 March 1919 Probate Belfast 14 September to John A. Peel solicitor. Effects £131 17s. 6d.
John Williamsons who might be your immediate line. (There were other Williamsons nearby, so it’s hard to tell).
Williamson John of Castleraw county Armagh farmer died 26 June 1935 Probate Belfast 7 November to reverend Henry Lamb clerk and Richard Hamilton McClelland farmer. Effects £92.
Williamson, Benjamin of Castleraw Loughgall county Armagh farmer died 16 September 1960 Probate Belfast 16 November to Francis Henry Williamson farmer and Sarah Jane Fleming married woman. Effects £2004 10s. 8d.
Above 2 wills should be in PRONI if you want to read them.
Benjamin & Rachel both signed the Ulster Covenant in 1912, so that tells you a little about their views on Home Rule. You can view their signatures on the PRONI Ulster Covenant site. Others signing immediately with them were John Halligan and John Williamson, so presumably friends.
Benjamin’s father:
Administration of the Estate of the late Henry Williamson, Kincon, Co. Armagh, Farmer, who died 14 June 1919, granted at Armagh 7 August 1919 to Henry Williamson, Farmer, the son. Effects: £134.