A little update, Cadac have replaced my whole base unit.
They asked me a few times if I had done a leak test on the new regulator, but as it was new to be honest I hadn't considered it faulty.
Their instructions also state to do a leak test if there is a leak, I made the point that as I didn't smell gas and heard no escape of gas I expected nothing. In our email exchange we discussed that a leak test should be carried out each time and its certainly something I will do every time from now on. I suggested their instructions should be amended.
A gas safe engineer colleague at work when discussing this said he is always surprised that we can just buy lpg etc. Apparently in a gas emergency the risk of LPG type gas igniting is twice that of natural gas, because it is heavier than air and sinks down so you are also unlikely to smell it.
Food for thought. Do those leak tests on your gas devices regularly