If ANY of the births were in Scotland, a question was ASKED on the Birth Registration [column 4] about the marriage of the parents. There were 3 questions in that column for the Registrar to write the response :
Name, Surname & Rank or Profession of Father
Name and Maiden Surname of Mother
Date and Place of Marriage
There was a short range of years these were not asked, it was 1856-1870. 1855 was the best year for information on a Birth Registration which included those 3 questions, then that gap of 5y, those 3 questions again were asked of the Informant at a Birth beginning 1 Jan 1871.
If you can find/download the birth of ANY children of Thomas BELL and Elizabeth CAMPBELL, those questions SHOULD be answered on the Registration...although they can be answered with 'unknown' or sometimes just a year of marriage and a place [Ireland] not the full date and exact place we are really hoping to see.
The IGI has 7 children born to those exact 2 parent names however they were born in Fife 1864-81 so its not likely to be your family. ScotlandsPeople.gov.uk/ has the 1911 Census for Scotland. Meg Greenwood / Oklahoma USA