I've never had a problem with the pressure limiting valve, which is what yours is. Unlike those crap `FAM' valves used on the last of the Clubbies here.
Either:
1. You are standing on the pedal too hard and forcing the valve to close the circuit off- or,
2. There is crud and debris blocking the little bleed holes in the cylinders.
Take the bleed nipple right out and ensure you can poke a 1.5mm drill bit in there.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

When this happens all you need to do is release the brake pedel a very small amount then it will go to the floor.
Cheers Pete

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A recent study found the average Aussie walks about 900 miles a year
Another study found Aussies drink, on average, 22 gallons of alcohol a year
That means, on average, Australians get about 41 miles per gallon

Kind of makes you proud to be an AUSSIE

Hmm interesting point, we were doing the 'pump pump pump hold release bleed nipple' rather than the 'release bleed nipple and push brake to the floor' method. Perhaps tomorrow I'll attack it with the pressure bleeder, that removes the brake pedal from the equation. Although the brake pedal at the moment is nice and hard and they work quite well, it's hard to tell what's going on at the back.

If you still had air in the back, no way pedal would be `nice and hard'...
Really, the rears do SFA, particularly if you have S rear wheel cylinders.
Many racers ran with no working rear brakes.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

In that case then, I think I'll leave it. It stops, reasonably well at that (the front pads are cheapo rubbish and they won't wear out!!)