Tony said the end maybe looks a little bit like any technical adapter, but that´s really speculative ;-)And this made me remember again a post on the Medieval Silkwork blog, where there are two pictures showing some sort of spooling/thread winding concoction. I have been idly speculating about this in relation to the London bobbin before, but now it makes even more sense to me.
In a normal household, even where a lot of sewing is done, the amount of thread needed is not too huge to wind by hand. Yes, of course it is faster to use a bobbin-winder or a ball-winder, but you could also wind your threads in the evening when it's too dark for other work or hand it to one of the household children to wind. For some techniques, it might not be necessary at all to re-wind your thread from the skein into some other form first, but you can take what you need from the skein directly and then re-store the rest. Even knitting is possible from an unwound skein.
But there are situations when this is just not practicable, and where some faster method of winding is needed - like in readying thread for the shuttles while weaving. And that is also the context in which the winding gadgets (which these things clearly are) are shown, in a weaver's workshop.
And this leads me to thinking that maybe the ends of the London find thing might be an adapter of some sort after all - and not a residue from turning it on a lathe (an interpretation I heard from a wood-turner once) or a whim of the maker. Maybe it was used on a winding contraption in the context of a weaving workshop?