In that era, in the NSW Church of England parish registers that I have accessed back as early as the 1970s as a volunteer transcribing the scribble of various clergy in those early registers, to more recent transcribing efforts even in this century.... Yes, there's no real rhyme or reason to see a 'pattern' to the witnesses. Sometimes there can be three or more 'signatures', sometimes the witnesses sign in full with clear strong firm handwriting, sometimes they scribble (although I feel that the clergy are by far the worst scribblers ever), sometimes the witnesses signatures are an Initial followed by a surname, sometimes you can clearly say THREE ADULT MALES were witnesses based on the clear full names easily read off the register. Sometimes you can say - hey, that person was not yet of full age, who gave consent for that marriage... I have one of my ancestors whose witnesses include a child aged 12. All valid, nothing odd at all, definitely a child by my 21st century eyes. But if you speak with experienced researchers they will likely remind you to consider the context - the then rules, then practices, then church practices, procedures etc.
Remember too that NSW did not have any divorce laws until the mid 1870s. So in NSW before civil registration commenced a clergyman had two options when HE filled out the various sections of HIS parish register. He could record either spinster or widow for the female and either bachelor or widow(er) for the male. So remembering that the clergy were responsible for obeying church laws and so the secular laws were not as significant as say the statute laws that apply in this century. In the era that Sarah married, Formal Marriage was a church matter, that the secular laws had to respect. Yes, de facto relationships were the domain of the civil courts.
So, the question you are asking re spinster could be better asked if we consider the alternative ... Widow. Queen Victoria became a widow when her lawful husband died in 1861. Until then, right throughout the realms of the British Empire and throughout much of the countries outside of the Empire but where the was a strong allegience to the practices of the Anglicans or Roman Catholics or Presbyterians or Methodists or other Christian denominations - a widow was either a relict of a formal marriage that had ended with the burial of her husband or any female with her young children to support and NO male known to be supporting that family group. So in a broad sense that includes not just how you or I would consider a 'widow' as a female whose husband has died. So a spinster could, in a broad sense in NSW in 1855 be considered a female who has no children and is not known to have a husband.
Important to also remember that the laws of England - particularly the Marriage Acts from say July 1823 and later, had NO effect anywhere except in England and Wales. But the 'Seven Years" laws from back in 1604 did apply right through the Empire, including NSW ... So a marriage in England was effectively terminated when a convicted person was transported to NSW as that was beyond the seas.
I am typing this into a tiny dialogue box. I will try to find the relevant threads that many experienced RChatters have contributed to regarding these matters, but you can look these matters up using RChats own search engine.
JM
