This is from Sheldon's Raleigh threading page: The easiest way to identify Raleigh-built bikes is by looking at the rear dropouts. Almost all Raleigh-threaded bikes have the rear fender eyelets located directly behind the axle, instead of above it.

So based on your pic of the rear dropout, it sounds like you should expect 26tpi threads.

I'm sure the bike will prove serviceable for your intended use. It would be cherished transportation in many parts of the world.