Hi Steve
I am having the same problem with my engine 190/200bhp which has a Scholar block. I have the Pace D/S system with the Brise tank mounted in front of the cam cover. The engine was re-built due to very high oil consumption. To date I have run just over 1,200 miles including the trackday at Combe, after running in on mineral oil (1.000 miles). Over 10 ltrs of oil have now been poured into the tank! Therefore, this has not cured the problem with the oil consumption. Furthermore, my cooling system is over-pressurising too. I can find no leaks in the system therefore, I have concluded that the air is entering the system via the head gasket under the compression cycle of the engine. The oil usage is a total mystery!
To conclude, it would appear that we both have signs of early head gasket failure.
Regards
John