MaximG
Well-Known Forum User
Look what I found!
https://www.ellbergs.se/product/hylsa-1-2-x-17-fyrkant
That's around 11-12GBP. Don't know if it's including VAT or not.
One thing though, they are not easy to find, but here they are!
But isn’t this a multi point socket rather than just the square, looking at the diagram.