In the bicentennial dictionary of W.A (volume 2, D -J), I see in the listing under Robert Gault, it is noted that he was in fact " possibly " Henry Gault.
It does not state why they think this, but assuming that they are correct then his details are as follows.
Gault, Robert, born 1827, died 27th of March 1875 (possibly Henry who arrived 31st of August 1853 per Phebe DUNBAR, expiree), married Elizabeth Jane Cunningham who died on 2 January 1875.
Children: Agnes, Emma Mary 1859, Jane Martha 1864 (Northam), William, Sarah Matilda 1866 died 1875, John Simmons baptised 1873, MaryAnn 1873 (York Wesleyan baptised 1875). Northam-York. Employed three ticket of leave men 1866 to 1872 including a carpenter in 1871.
If you believe this is him then there are also details of the sons, John Simmons Gault and William Gault that I can give you details of.
John.