Old mail

I came across this very old letter in the small drawer of the sewing machine I 'inherited' from my godmother many years ago.  I thought I had lost it, but today it appeared among other old papers I was clearing away.
It is a  letter of condolence addressed to my godmother because her sister had passed away a few months before. But I do not know who wrote the letter, who was living in Montilla in 1953 and why she kept this letter among her sewing things.
 So many mysteries to be solved!!