Someone told me that they didn’t actually need to do this in the church - the minister could have come discreetly to Balmoral. Perhaps a Scottish poster might know the rules on this!
This is true. Scottish marriage rules are quite different from England and Wales. People can get married anywhere they like - outside, on a beach, top of a mountain - by a member of the clergy. This has always been the case and I have seen lots of examples of people being married in their own house, at the minister's house or elsewhere. This (in my experience) was more common when people wanted to get married in a hurry - when the groom was being sent off to war or when the bride was pregnant. Banns are not necessarily read. There was also the option to marry "by warrant of sheriff" in front of a solicitor and witnesses rather than religiously and this option was often used by couples who either weren't religious, or who were already living together.
However, there is still paperwork. The minister still fills in the marriage certificate which is sent to National Records of Scotland. There still needs to be 2 witnesses other than the person officiating.
There is no way that they were married legally - there would have had to be at least three other people involved in making that happen on the day, and then more people making the official record disappear and changing lots of other records too so that the numbers run consecutively. No way. As with all other conspiracies it would need a lot of people colluding to make it happen and I don't believe that not one of those people ever talked.
Similar to the "baby" - Queens typically don't give birth alone on the bathroom floor, there would have been medical attendants during what would have been her 10th pregnancy and assistance during labour. She may have been dumpy but seriously, concealing a pregnancy/birth when you're the bloody queen and spend your life having other people do stuff for you? Again it would need so many people in on it.
She was clearly fond of John Brown and yes I can believe they had some sort of unofficial handfasting ceremony or whatever. But official marriage and baby definitely not.