I use numerous fonts in one of my sidelines and have compared your
photos to my fonts that are similar.  I can say that yours is close to,
but not Old English, Blecket, Christmas Card, Clerestory or Cloister.

At http://www.fonts.com/ are over 170,000 fonts to choose from.  These
are called "black letter fonts".  There are a couple that come close.
But in order to get an exact match you may need to photograph the ones
you want to copy and then print them out on the desired surface,
preferably with a laser printer.  The particular font may or may not
have a name and may be unique to the particular organ builder.

Vincent Morgan
New York City