Thanks again.
When I first installed the master cylinder a few months ago I forgot I ordered the gaskets which sit under each master cylinder. I had to put on a new base plate as the old one had a larger hole for the engine steady.
When I put in the second kit I put the gaskets on but did not tighten it down enough on the back bolt.
After partially bleeding the system I got my brother to push the pedal and saw the movement in the back bolt. Some smarty had replaced the 1/2 inch bolt with a 12 mm one so I had to use two different spanners to get it down tight.
I will try the bleed again this weekend and work out whether to replace the master and the slave cylinders and probably go and see John Schmidt next Monday.