Originally Posted by
NormanF
You could have a bike shop file the bottom bracket housing to the more common 24 TPI British standard, for which a bottom bracket is readily available.
Or you can buy a Phil Wood 26 TPI bottom bracket cartridge, but that's an expensive solution. A Shimano UNO-73 bottom bracket will work with vintage Raleighs...
Another solution is to have it converted to Italian threaded, Italian threaded is slightly larger then British threaded, but has the same pitch, by boring it out and cutting Italian threading you are cutting threads into metal rather then just moving them around. You need a shop that knows how to do it though, Italian threaded parts are still quite common. BTW Raleigh threaded BB's are often 76mm wide, not 71mm wide, which is the width for Italian threaded.