After finding the previously posted marriages I did some more thinking and also read through all posts in this thread.
As a consequence I tried some more searches with some interesting results.
One thing that had been menioned in letters from Nicholas Trewheler was that Ann Trewheellar daughter of Richard and Martha (nee Snow) had married someone named CLARK in Russia.
But a search on the surname CLARK produced an unexpected result:-
James Truewheeler Clark born 7th February 1826 and baptised 18th October 1826 British Chaplaincy, St Petersburg, Russia
The unexpected?
Parents were Charles and ELIZABETH Clark!
I have found eight children for Charles and Elizabeth between 1821 and 1839 with all baptised at the British Chaplaincy.
George Richard - 1822 (born 1821)
Elizabeth MARTHA - 1824
James Truewheeler - 1826
Nichol Finlay - 1830 (born 1828)
Jennett Helen - 1830
Grace - 1833
Edwin Charles - 1835
Ann - 1839
Question - do we have a previusly unknown daughter of Richard and Martha Trewheellar??
The use of the name MARTHA with the second child would certainly indicate the possibility.
But what I cannot understand is the name JAMES Truewheeler Clark.
James was not a name used in this branch of the Trewhella (sic.) families and that then makes me wonder whether Elizabeth, if she were a Trewhella, might be from elsewhere.
This seems unlikely however.
Another search that produced some interesting results was on the surname SNOW.
I searched this mainly because there was a note amongst my records suggesting 'his mother was a Miss Snow'.
This was referring I believe to Richard Trewheellar whose grandmother was Martha Snow and whose mother has apparently been recorded as Anna Dorothea Henriette Berg.
However I searched out of curiosity and came up with the following all baptised at the British Chaplaincy, St Petersburg:-
John Truewhellar SNOW bp. 25th February 1815 s/o John Truewhellar Snow and Ann
Robert Trewhillar SNOW bp. 13th March 1817 s/o John Snow and Ann
Anne ... SNOW bp. 20th July 1819 d/o John Snow and Anne
(Another unsourced record shows her as Ann Trewkeellar Snow)
And right here we have a rather peculiar problem!
My first thought when I saw these entries was that the formation of the names was very similar to that used in Chile where the maiden name of the mother is appended.
However if this were correct then (e.g.) Robert Truewhellar Snow would be Robert Truewhellar son of John Truewhellar and Ann (whose maiden name was Snow).
Perhaps this is where the above reference to 'Miss Snow' originated.
But as I have said - another record indicates that John Trewheellar's wife was Anna Dorothea Henriette BERG.
The obvious solution to the problem is that there is no problem at all and that Robert was actually the son of John SNOW.
At this point I do not believe that to be correct.
What I think right at this moment is that these three are actually children of John TREWHEELLAR.
Robert in 1817 would be about the right age to have been Robert Snow Trewheellar who married Helen Varantsoff in 1839.
According to notes in a letter from Nicholas Trewheler there were two daughters to John and Ann Trewheellar and the Ann above could logically have been one of those.
But the baptism of John indicates that John Coulter Trewheellar (born Kent 1813) must have died before the age of 2.
More information found .................. but a lot more thinking to be done!
CT