I certainly have some Wylex ones wired in the 'less usual' way. It seems that you can probably add Hager to your list, albeit this is over 7 years old (click here) - where, as you can see, it was said:
I contacted Hagar technical regarding this and their answer was
"It makes no difference to which the incoming or outgoing side are connected, and will not affect the operation or safety of the device"
So for your device, the the manufacturer had marked the casing indicating an in and out, so direction mattered. Was your RCD possibly a RCBO? They are asymmetric and can only be fitted one way round in a CU. Just a thought.
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