Once again Binos accumulates a piece of knowledge from Pprune. Thanks Richard.
But bear in mind this is a 6Gb disk which I fdisked just last week before reinstalling W98 and a few regularly used programs then defragged. Now Pitstop tells me the vol size is 6.6Gb, Used space 1.1Gb, Free Space 4.4 Gb (

) and my overall disk health is Average; Medium levels of disk fragmentation.
Sheesh, does it ever give a clean bill of health?