Thanks, ayk, there wouldnt be any point in bringing an earthed "artifical hand" to the SMPS if it already had earth inside it.
pdenisowski in post #1 above kindly delivers the info.
It is a metal foil, but does that metal foil get wrapped right round the power supply.?
PSU (eg laptop PSU) is not "handheld device", but it couLD be held in the hand, so it needs the metal foil to be wrapping it during conducted EMC.
What about eg drills which have an offline psu in them, but often have holes for vents in the casing....the wrapping of the metal foil will obscure the vent holes....and cause the electronics to overheat?