Thanks Judith
The registration in NSW BDM certainly applies to Catherine Sinclair (nee Briggs). The John is of course her father, John Briggs who died in Mintaro, SA.
i have a Henry John Sinclair in my family tree (Ancestry) who was born around 1845 /45 in Oundle, near Winwick in Northampton, UK. The listing is for a Henry Ruddifer Briggs, with Catherine as the mother, no father listed. Informant was John Briggs, Grandfather (of Henry).
I cannot find any further record of Henry, other than to assume that he became Henry John Sinclair. The death certificate for same lists mother as Catherine Briggs and William Sinclair as the father, yet Henry was born prior to both William and Catherine meeting (one assumes since William hailed from Larkshire, Scotland). Do you have any information on this Henry to confirm that he is one and the same? I think in 1848 after William and Catherine were married but before their son William John was born, that Henry simply became known as Henry Sinclair. Don't think colonial records were that specific.
Can I ask if you are related through Catherine? If so, we are distant relatives!
Julie