I have a US - Rest of world transformer that looks a bit like that.
You slide a little lever and it exposes different pins that pop out.
You've got BS1363 which you have to pull out and turn 180degrees to lock
2 pin Europlug flat or recessed (pull out a kinda stalk and turn the pins until they're tight.
Aus/Nz: pull and twist into position these also double up for 220V NEMA pins for China.
Doesn't have BS546 though.
Very flimsey design it only ever draws a couple of watts though.
