Okay, here is where I've been going with this.
LesleyB wrote:
1. I wonder if George was originally registered in an OPR (if indeed he was) under another surname e.g. his father's? (in which case it will not be possible to search for him really using either SP or IGI, as both require a surname...)
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I had a look at the Hugh Wallace site for the Channelkirk OPR batch covering the likely date range, but no George of any description, which was kinda what led me to no. 2.
Unfortunately, this is one of the parishes where only female births appear on the online IGI

Most frustrating. There may well have been dozens of Georges born there in the right time frame, but they are invisible until I can scroll through the microfilm. He was not down under the name of dalg*, anyway.
LesleyB wrote:2. Would it be possible that May had been away somewhere else (for work?) and come back home again between censuses, in which case your George could have been born anywhere... I take it he claims to be born in Channelkirk on the 1861? ( I can see this is what he says in 1881)
Yes, he is consistent in saying he was born in Channelkirk in all censuses. May was a "House Keeper" in Ugston/Oxton, Channelkirk in 1851, living with her father George the tailor. I looked all around to see if there was a household where she might have been employed, with a single or widowed male, but nothing obvious. I assume she was just House Keeper for her father.
LesleyB wrote:3. Might the family have been something other than established church?
… Where in 1877 did George marry - all CoS? Thing is, even if he wasn't originally CoS he may still have married in CoS as that may have been his wife's family's church. If there is no indication of another church, it could be a wild goose chase and also very time consuming to check all other possible churches in the area, if indeed May stayed in the area at the time of conception and George's birth.
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How does he word who his mother is? Has he been really clever in his quest to look "run-of-the-mill" and said "May Dalgleish, m.s. Dalgleish"?? Or is there no m.s.?
He has been clever (as befits a schoolmaster), as you'll see:
George was married in Douglas, Lanark
After Banns according to the Forms of the Established Church of Scotland
Father: George Dalgleish, Tailor Master, Deceased
Mother: May Dalgleish, M. S. Dalgleish
Andrew Dalgleish, witness (there is an Andrew Dalgleish in the same household as May in 1881. He appears to be her cousin, as his mother Jane is Head, he is Son and May is Niece) Have tracked him down and he is the son of George Sr's brother John. )
James Robertson, witness
LesleyB wrote:I suppose there would not be anything so useful as wills or other documentation for this family?
Nothing directly relevant, I'm afraid. There is an inventory for Jane Stewart or Dalgleish, spouse of May's half brother George… but it's not likely to be full of revelations on her father-in-law.
There is a will for William Stewart Dalgleish who died at Sydney, New South Wales in 1894, testate. This is the name of one of the son's of May's half brother, but it may not be the same person, since that William was born in 1872 and would have been quite young to have written a will, let alone one of 11 pages.
Currie wrote: I was just passing by the unanswered posts and I noticed yours sitting there looking thoroughly neglected.
I appreciate your compassion! I wondered how long it would take someone to click on "view unanswered posts" and put a kind note in.
Currie wrote:According to the 1851 census there were only three George Dalgl* aged between 9 and 99 in the whole of Berwick. Besides your fellow, aged 47 in Channelkirk, there’s a 41 year old George Dalgleish in the Greenlaw district, and a 42 year old George Dalgliesh in the district of Gordon.
Any chance either of the other two may have dabbled in Tailoring or are there any other GD’s with that trade in neighbouring counties?
No sign of any other tailors by that name, although there are plenty of George Dalgleishes about. Just in the Channelkirk OPRs there was one born 1776 one in 1800, one in 1802 (the tailor), one in 1821 (more about him later)
Currie wrote: Any luck with George junior’s death certificate? What was the parent story then?
When George died in 1910 his mother was still living. The name of his father was left blank and the mother was "May Dalgleish, Dressmaker". The informant was his son named, guess what, George.
Currie wrote: It would be handy if young George had some siblings. Perhaps there were some that we don’t know about.
If there were any, they didn't appear on the censuses with either their mother or their brother...
Currie wrote: Even if the prospect of legal action had long passed it’s probably not the sort of thing that a schoolmaster with a certain social position to maintain would want known. Then again, such a schoolmaster probably wouldn’t want known that he was illegitimate as would be revealed if a father’s name wasn’t given.
Yes, and it turns out he was marrying the daughter of the local schoolmaster in Douglas, Lanark, which is probably why he felt he had to put something for the father's name...
Joette wrote: If he was illegitimate he may have been covering up the fact -I would say that was the most obvious answer.
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I would be very surprised if he was stating officially that he was born of incest-I think people would go out of their way to cover it up.
Yes, I think you're right, Joette. He was most likely just wanting to put something in the box for father's name when he married the schoolmaster's daughter (far away from his birth village)
Thanks, everyone! All your questions and speculations made me look more closely at this family and I found some interesting things:
On the same page in the Channelkirk OPR Births we find both May's birth and the birth of another George:
Dalglish
George Tailor Ugston and Elisabeth Dalglish his Wife had a Daughter born 21st January 1829 and baptized 23 March 1830 called May Dalglish
Dalglish
George Tailor Ugston and Sophia Purves had a Son born in fornication 26th April 1821 and baptized 29 May 1831 called George Dalglish
So… May had a half-brother 8 years older than her, also called George. The plot thickens! Why did he decide to baptize him 10 years after the birth? May's baptism was also late. All the other baptisms on the page are within a few months of the birth. I think the kirk session records might shed some light on this and they supposedly DO exist up until 1850, so maybe there will be a clue there. It does sound as if they remained C of S, even if they didn't observe all the rituals at the usual times...
I followed May's half-brother George down through the censuses. He lived with his mother Sophia Purves who left Channelkirk but never married. Sounds like May's life as well. This George had the good sense to marry in 1855

and gives his parents as George Dalgleish, Tailor and Sophia Purves, Farm Servant with no indication that he is illegitimate.
I also tried to get to the bottom of who May's mother was, since she was also surnamed Dalgleish

There were several Elizabeth Dalgleishes born in Channelkirk around the right time, one being George the tailor's sister... Not wanting to go there, I looked for another one. This one looks most plausible to me because of her mother's name:
Elisabeth Dalgleish
Birth: 18 June 1804
Father: Thomas Dalgleish
Mother: May Linsay
Can't find George and Elisabeth's marriage, although May's birth certainly makes it look like they were, indeed, married. I assume she died before 1841, possibly shortly after May's birth since there don't appear to be any more children. Although the burial records are supposed to exist for Channelkirk at that time, I don't see a possible death in the OPRs. There may well be a gap, since there are no Dalg* deaths after 1826 in the Channelkirk OPRs
It looks as though George the tailor's father William and Elisabeth Dalgleish's father Thomas may have been brothers

I wonder whether there would have been some discussion about this in the kirk session records if George and Elisabeth were, indeed, first cousins. This is assuming they were all born in Channelkirk, which may not be the case.
It seems that I still have a few things to look at before giving up:
1) scroll through the births around the time of George's birth and see if I can spot him (or possibly much later given the time lag between birth and baptism in this family).
2) Look at the kirk session records that do exist just in case. Surely there should be something about George the tailor, since he reportedly had at least one illegitimate child in addition to his legitimate one.
Any other ideas?
Thanks again,
Sarah