Ah, now hang on, more info, I'm learning the terminology which will probably help a bit!
In the CU there is the main red switch followed by one RCD 80A/30mA/240v with 3 MCB's 32/240, 16/240 and 6/240. Then there is a 2nd RCD 80A/100mA/230v with 2MCB's 40/240 (unused and off) and 32/240...