French Wonder Brassard* - arm band light. Front and rear is together, rather clever. My father used to ride with one umpteen years ago. They were marketed to cyclists and walkers. They are inspired from old lanterns used by railway workers.
Can't see why it couldn't be strapped to a right fork blade if needs be; in fact if it was to be strapped to a bike anywhere it would be the logical place on a more vertical position traffic side (for the UK). The measurements seem to correspond too. Please please please tell me I've won this retrobike guessing game and you will leave a bottle of Pernod at the Inn
* not a Wonder Bra, that's something entirely different