Is there a way to check integrity of earthing provisions?
In the USA this is called a Ground Bond Test. There is specialized equipment that sends a high current through the grounding/bonding conductors, measures the resultant voltage, then calculates the resistance to ground.

In a well-grounded system, this voltage will be very low.  If the voltage exceeds a certain threshold (meaning that the resistance to ground is too high) the test is automatically halted.

In your case, you would first find (or create) a known-good earthing point.  Then you would perform the ground-bond test from this point to the ground connections of individual machines/panels.

Ground-bond testing equipment is expensive; you may wish to find a testing agency that can rent it to you, or which will perform the tests for you.