I thought I'd update this post with some other information that has just come to light, in case anyone can help with it.
The name of Patrick Austin born around 1805 has been put forward as a possible match for my GtGtGrandfather. He had sons Patrick born 1828, Arthur 1833, Henry 1834 and James 1835 all born in Derrinver, Montiaghs, Armagh. Any help with any of these would be very much appreciated.
Ken