Just opened the CU at work, as we need to add another circuit for some A/C
in the server room.

There is a 32A breaker marked as Spare with a single 2.5mm wire inserted (So
it isn't spare then I assume!)
Now, one part of me says this is wrong, it should be a 20A MCB as it must be
a radial, but if this were a ring circuit, then I could spur off of it, so
the spur would be protected with a 32A breaker.

The installation has passed safety inspections, should it have?

Sparks...