Brackers, I don't post here much, but I feel moved to do so after reading your thread.
Going on the information you've provided, your installation is EXTREMELY dangerous!
On a TT installation (earth rod) the Earth Fault Loop Impedance is relatively high compared to a TN system. If we say your installation has a typical TT EFLI of 23ohms (to keep the maths simple) and a live conductor comes in to contact with an earthed metallic part, ohms law tells us that a fault current of 230v/23ohms=10amps will flow. As you can see, this isn't enough to blow a 13A fuse, never mind a B32 MCB. It is for this reason that all TT installations MUST be RCD protected - the whole installation. This isn't a new thing either, and has nothing to do with the 17th edition's calls for 30mA RCD protection on nearly everything. Normally a TT installation will have a 100mA RCD as a main switch - if yours defintately doesn't have an external RCD/ELCB, then you're in very real danger because whilst that fault current is flowing, ALL earthed parts of your installation will be at 230v!
This is even more worrying in your case in that your 'electrician' KNEW you had a live-earth fault (as it was causing the 30mA RCD to trip). Not only that, but there's also the lack of main bonding to the incoming gas/water pipes. If you had main bonding, when all the earthed metallic parts rise to 230v due to your earth fault (which you DO have because the RCD was tripping!) - everything else that was bonded would also be at 230v. Not great, but there'd then be no potential differnce between an earthed part and the kitchen taps etc. Without any bonding, the earthed parts will be at 230v, and the water pipes will be at local earth potential (ie 0v). This is bad bad stuff mate.
I'm not trying to scare you, but I hope I've managed to explain just why your situation is so dangerous.
PS. BaS & Martin, I know I said I wouldn't post here, but this was too important. Peace.