British residing in Mexico

I'm hoping to find information on how to get information on some family members who lived in Mexico, including my great-grandfather who died there.    My great-grandfather was John James Davidson, who was Brittish - I believe he was born abt 1865 in England.  His mother was Irish and had at least one sibling born in Ireland....   so he may be listed as English or Irish in records.  He was a mining engineer working in Guanajuato Mexico about 1900.   Family history says he died in Mexico. He married my great-grandmother Margaret Etta Hicklin in Fairview, New Mexico prior to her family moving to Arizona.  He had sons born in either Arizona or Mexico between 1898 and 1902 - Henry James and Oscar Otis.  He had a third son who died young Thomas Wardell Davidosn who I've found no record of.  After his death Margaret married Robert McCormack, also a Brittish miner.   One of these two was noted  by the family as being the British Consul, but I have no idea what that means or which for sure.   Robert and Margaret had 2 daughters:  Margaret Etta (b. 1905)  and Josephine Carlotta McCormack (b. abt 1906) in Mexico.    Margaret, her children and Robert fled Mexico about 1913 on a train draped in a British flag, supposedly sharing the railroad car with a load of dynomite.   The family lived in Texas from that time.  Margaret eventually marrying a third time to Wallace Littlejohn.

I would dearly love to find out more history about the British miners in Mexico, the Guanajuato history, and how to find records for any of these individuals. 

Thank you,

Trudy