[S LATHERON (RIP)]

seasons greetings.
I guess the frozen brake could be a combination of things.
1]Older Brake fluid absorb water and expands, looses its viscosity and ability to operate the system properly and causes corrosion inside wheel cylinders in time
2] have you checked the adjustment on the master cylinder. If the push rod that pushes the MASTER piston forwards has stuck in the on position, fluid is trapped in all the wheel cylinders. Locking all the brakes in the on position.
3] The answer to the above may be in the linkage, Or a weak or worn return spring at the master cylinder or seized pivots in linkage due to limited use.
4] I know other owners of vintage vehicles that reset the brake shoes so that they have to travel further inside the drums before making contact with the drum face. Although it means the shoes have further to travel on the first stroke of the brake pedal but this gives better working clearances and less risk of shoes sticking to the drums while parked up for storage.Also as the brake pressure is released the shoes are less likely to bind and cause heat build up
5]As little as a lack of a clean breather hole in the top of the brake master Cylinder resevoir can be fatal.
I had a similar experience with a 1958 military Ex RN land rover station wagon. Drove round a long curve at 50 mph only to find traffic stopped ahead of me. I jumped on brakes and took TO LONG to stop! Finally stopped only when my heart was in my mouth, approx 6 inches off trunk of car in front. On investigation after a rather nervous and slow drive into a side road. i found a hard layer of mud set on top of the vent hole that lets air into the header tank of the brake system. As you apply the brakes the fluid is forced into the pipes, however if air cannot enter to replace the fluid used then there is no way the brakes will work properley as the lack of air causes a vacuum inside the system reducing effieciency. A bristle from a wire brush restores ventilation in seconds.
I hope that you are able to collect your new "Commer" soon and give it the use and TLC it deserves.
PS, In 1974 i joined a chrysler car dealer ship to sell the commercial vehicle range in the north east of the UK, Commer, carrier [Bantam] then the Dodge range of trucks. Humbers were cars only in uk then.
Regards Stephen
F60S LAAT 1944