I've just re-read the OP and if you have correctly relayed the information from the electrician I think it's looking a lot like he is incompetent, we have all been been concentrating on the 32A MCB but now I realise I misunderstood his FCU fuse rating, it shouldn't be 13A as the heater elements usually only have 0.5mm² flex. The fuse could usefully be 3A or 5A max.
Following on from Erics excellent post I'd possibly suggest the new dedicated radial would be well designed if using a 6A MCB and double pole switches without fuses. However FCU's tend to be cheaper and argueably more convenient.
Sorry, I missed this earlier post.
Actually, without thinking, I mentioned a 13A fuse, but agree with you that it should be less. I don't think the electrician specifically mentioned a particular fuse rating. I've just looked at the instructions that came with the element and they also don't mention fuses, only a double pole (all points of contact?) switch and the requirement of a 30mA MCB, so this does seem to fit in with what is being said.