Maybe just a little recollection from my time working for Marconi in New Street (1973-1978).
I worked in Building 46, initially for Jimmy Gould on HF naval radio systems (ICS3) and then for Mick Cranmer on broadcast transmitters (250 kW long wave).
In the lab there were many useful little bits of homemade test equipment, of course built into Eddystone die-cast boxes. One in particular was a fuse tester - the top was covered in fuse holders of all different shapes and sizes. There was a push button labelled ‘Test’, a red light and green light.
The red light was labelled ‘Fuse is dead’ while the green light was labelled ‘Fuse was good’.
Yes, inside the box was a power supply that charged up a big electrolytic capacitor, and when the test button was pushed, it fired a latching relay to light the appropriate indicator, and at the same time discharged itself (quite explosively) through the fuse.
Hence the label ‘Fuse was good’.