I'm now trying to figure out what size bottom bracket I'd need for this bike. I made a bunch of measurements, and came up with this:
BB shell width: 69.75mm

I measured the diameter, but didn't know whether to measure it inside the threads, or ouside (do you count the thickness of the threads in the diameter or not?)
Inside the threads, the diameter was about 33.4mm
Outside the threads, the diameter was about 34.8mm = 1.375" (1 3/8")

I didn't get the threads per inch count.

Looking at Sheldon Brown's bottom bracket chart, I'm left wondering which mine is. It looks close the the Raleigh proprietary size, but the chart says that applies to British made Raleighs, which mine is not.

Or, maybe I should just take it to my LBS and ask them about it.