In my absence a foreighn electrician atempted to repair a socket without switching off the fuse box. I was told he accidentally touched the wires with his screwdriver and expected that that would automatically switch off the fuse box. When it did't he said the fuse box was faulty.
If he was to touch live and neutral together, or live and earth together, one would expect the fuse to blow or the circuit breaker to trip.
However, if he was to touch neutral and earth together, he may have been expecting an RCD to trip. It doesn't appear you have an RCD, as your wiring is older. If you don't physically have an RCD, this doesn't make your consumer unit faulty - just dated.
Anyhow, it's an older installation, it is what it is.
If he was adding to or altering the wiring, he may insist on some kind of upgrade.
I'm not sure I like some of this bloke's method of working and testing, would be interested to see what his standard of work is like.