You have taken the 10 most common names in Scotland to use in your calculations.
Surely most of the 'irregular' marriages at Gretna Green were non-Scots?
Yes, probably. I only did it that way because you can't search in the SP index without putting in some sort of search parameter. Several of the same names - Smith, Brown, Wilson for example - are also among the commonest surnames in England.
...Divide that by the number of years from 1855 to 2016 (162) and that would mean that 6506 weddings a year, or 18 weddings every day of the year including Sundays, were conducted at Gretna (Green) or Graitney.
But there is no central depository of Gretna Green marriages therefore you have no idea of how many irregular marriages were performed.
You would have to call it the X factor.
No, but I quoted the estimates of the ministers in 1793 (60 per annum) and 1834 (300-400 per annum - that is, about
one a day, not 18 or anything near it), and of course there would have been none at all after (I think) 1939 when marriage by declaration was abolished and civil marriage was introduced.
You called it Gretna (Green) or Graitney.
SP call it Gretna with no acknowledgement of a Green.
Of course SP don't call it Gretna Green. Gretna Green is just one settlement in the parish/RD which SP calls 'Gretna or Graitney' from 1855 to 1968. In fact the ex-tobacconist described by the minister in the 1793 Account, Joseph Paisley, actually moved from Gretna Green to Springfield, in the same parish, in 1791 and carried on his business there until his death. So trying to consider Gretna Green in isolation from the rest of the parish is pointless.
I don't dispute that there a lot of irregular marriages were performed in the parish of Graitney or Gretna, most of them in Gretna Green, which was the first village or hamlet after crossing the border. I don't dispute that most of the couples married irregularly in Graitney or Gretna, whether at Gretna Green, Springfield or anywhere else in the parish, were from England.
What I do not believe is that there were so many of these runaway couples that the total number of marriages performed in the parish of Gretna or Graitney amounted to one in six of all marriages performed in Scotland. I have produced some evidence, some it of based on contemporary documentary evidence, and some based on research, admittedly quite crude, using actual data available on the SP web site, all of which suggests that one in six is a gross exaggeration. I have seen no evidence of any kind to support the assertion that the one in six is correct. If and when someone provides me with such evidence I will consider it, but until then, what I have researched and presented here suggests to me that it is nonsense.