Ever seen this?

Yes! I have a couple! Very useful especially if you have your equipment in a stand like the 8000 system. It means you only need one mains lead! In the UK it also means you don't have to cut off the original 2 pin plugs.

I don't suppose audiophiles regard them with much affection though - they don't cost £1000 a metre!

I junk these crappy old 0-class extension leads all the time. Now I know where they end up.

These cost less in Finland, new in the store...

Note: The mentioned extension lead has "continental" connections with a british connector ;) It's not a big deal, but it's not the same You sampled ;)

Of course not, but then you just replace the plug. I guess the brits are very experienced at that

A lead with similar connection arrangement as shown in the auction would be basically illegal over here, because it would allow old 0-class equipment (with a round non-earthed plug) to be used in rooms that require earthed mains wiring, where they would not be safe. I strongly suspect it is self-made as well.

Maybe these are not seen in Europe but in the UK they were supplied when you bought a system. The equipment all came with 2 pin european style plugs which would not work in the UK so instead of changing the plug, which would be illegal as the mains plug has to be a moulded plug, B&O supplied one of these. As Peter says, they are very useful indeed as it means that your 5000-7000 stack system or indeed the earlier set ups from the 80's like the 6000 or 8000 would only use one plug socket. If I needed one I would pay a fiver for it.

Most vintage B&O systems you find in the UK have had their rather nice 2-pin plugs removed and had either normal plugs attached or these crappy square (I think made by masterpieceofcrud or some similar name) one-off 3-pin mini plugs with 4-way extension. Pointless with class II equipment but I guess an 'extra' chargeable service offered at the time.

beaker:

If I needed one I would pay a fiver for it.

But I bet you'd still rather have one of these

Those ancient extension leads actually have one advantage (unless you have kids) - they don't have those pesky child protection mechanisms. I actually once had a wall wart type power supply disintegrate in my hands when I tried to coerce it out from one of those! Exposed live wires were left sticking out...