Main supply side earth leakage tripping

[Spark123]

New consumer unit would be my approach, given the old one is not type tested as well.
RCBOs tend to be single poled whereas in a TT system it is better to have earth leakage protection switching all poles. You can get double poled ones for a GE board but are two module width.

 

[Brigadier]

A new cu appears to be a much cheaper option, too.

 

[JohnD]

and I stll say try to get a supplier's earth, then you can dispense with the spike and use SP RCBOs.

 

[bernardgreen]

Looking at the photos I cannot see a wire the to top earth terminal, just two to the bottom terminal. Without a connection to the top earth I cannot see how this device can trip. Unless the mechanism is mechanically failing.

Or does this type have both earth terminals at the bottom.

Probably left in place but disabled to provide a means of isolation while changing the CU.

and I stll say try to get a supplier's earth, then you can dispense with the spike and use SP RCBOs.

There are advantages of being TT provided the ground rod remains low impedance and in some circumstances a PME ( neutral derived "earth" ) is not as good as a TT earth.

 

[Spark123]

Both E and F terminals are at the bottom, E - electrode, F - installation metalwork.