Peter Easthope wrote:

A Luxo L-1 lamp in Britain would have a three conductor flex. All
such lamps I've seen in North America have flat two conductor lamp
cord. The width fits closely in the square Luxo tubes.

Don't know, I've hankered after one, but don't own one.

A L-1 in Britain has a round flex; correct?

I notice the manual shows the double-insulated symbol, so 2-core flex
could be used which would normally be flat, though you /can/ get round
2-core flex.

While most UK plugs and sockets are BS-1363 square 3-pin, the older
BS-546 round 3-pin plugs and sockets are still acceptable and available
brand new.

The even older BS-372 round 2-pin are marginally smaller and belong in
museums, the same smaller spacing is used in BS-4573 plugs which are
typically only seen in moulded-on versions, and exclusively used on shavers.

Other than that, there are proprietary round 2 and 3-pin inline
connectors not intended for plugging into wall sockets, which conform to
the general BS-5733 safety standard, I use them on all my power tools,
annoyingly these are similar but not mateable between manufacturers, e.g.

https://www.mkelectric.com/en-ar/Products/WD/PortablePower/duraplug/Leadconnectors/Pages/LCP102.aspx