Thank you very much for the info that have provided which corroborates the info that we have pulled together from various family members.
It would appear from the lack of either a Scottish or English marriage certificate that Mary Ann Little and Charles Perry did not marry.
Likewise it would appear that the birth of their son Charles was not registered.
It is noted that Charles Perry's occupation is recorded as a railway labourer and as such he would go to wherever the work was.
On 13/08/1846, construction work started on The Glasgow, Kilmarnock, Dumfries Carlisle railway line which ran from Carlisle to Gretna Green and then via Rigg, Lowthertown, Eastriggs, Dormock, Annan, Cumertrees, Brass well and Noblehill, to Dumfries.
This section of line was opened on 23/08/1848 with the remaining section to Glasgow being completed on 28/10/1850.
Given this range of dates ie 1846 to 1850, it now seems more than likely that Mary Ann Little met Charles Perry when the line passed through the village/town where she lived and she took up with him, becoming pregnant in 1847/1848 with her son Charles being born in 1848/1849.
When his work on the line was complete in 1850, it would appear that Mary was pregnant again, and it appears that they upped sticks and went to the next railway job in London where their daughter Margaret (my maternal great grandmother) was born in 1851.
Clearly something significant occured to Charles Perry and his son, (did they both did???) as by 1861, Mary Ann and her daughter have now taken up with Joseph Jones with whom she moves to Hatfield and has several children before dying in 1874.
Once again many thanks for your help in exploring the Scottish side of this story.
Who knows, one day something may turn up which fills in the gaps in this story wrt to Mary Ann's place of birth and family and what happened in the 1850's.
Stay safe.
Best regards
10dorking