Thank you for your message.
I always thought that Margaret was actually originally from Dublin. I found a marriage notice in the Sydney Morning Herald from 30 November 1848 which refers to her father being Andrew Field, of Sydney, late of Henry Street, Dublin.
"On the 16th instant, at Melbourne, Port Phillip, at the Church of St. Francis by the Rev. Dean Coffee, Mr. James Doyle of the county of Wexford, Ireland, brother to the Rev. Thomas Doyle of New Ross [Ramsgrange] in the same county and relative of the late Right Rev. Dr. Doyle, Catholic Bishop of Kildare and Leighlin [pretty sure this is not correct] to Margaret Isabel, second daughter of Mr. Andrew Field of Sydney, late of Henry-Street Dublin and god-daughter of the Lord and Lady Ventry, Birwan House, County Kerry, Ireland [again not sure if this is true?]"
James was born in Tombrick, Newtownbarry (now known as Bunclody), Co. Wexford. I don't know when he left Ireland and/or arrived in Australia. I am his great-great nephew.
I also found reference to James being landlord of the Cerberus Hotel, Morris St., Williamstown in 1877.