New wheel cylinders were sourced from the local motor factors. These turned out to be very reasonably priced. After looking through the catalogue it was determined that my rear brakes are from a 1.8 or 2.0 Sierra estate car. This seems to tally with the fact that these are the bigger, nine inch, drums. The wheel cylinders were given a couple of coats of Hammerite to prevent rusting.
After that the new brake shoes were fitted. These were bought from EBC's online shop. Free next day delivery too.
The brake drums will be fitted later, after the hand brake cables are attached.