Dan
Yes, he was right (well done) Robert de Boron wrote this 12th/13th century.

Arthur was first mentioned by Ninnius, a 9th century monk.

These: sword in the stone/under stones/in anvils/in molds could be embellishments or maybe Arthur did something like this. It fits my agenda.
There's quite a gap between the the 9th and 12th century though so from my point of view I'll have to be careful how I explain this.

Cheers

Pieter B.
Actually reminding me of something I had forgotten. Thanks!

There is one flaw with the idea of drawing a sword from a casting mould-- they wouldn't be anywhere near ready to use. Even a high quality casting would still require finishing, hilting up, sharpening, and polishing.

Not to mention that unless you let it cool in the mould, which would take a fair while after pouring as the mould would insulate the metal to some degree, it'd be too hot to pluck directly out anyway!

Thus making it The Sword in the A&E Dept. Maybe the Lady of the Lake was an ER triage nurse...

I agree with those who commented to the effect that the sword in the stone story is pure fiction - it sounds to me much like the sort of tall tales usually told about a culture-hero to justify his legendary rule and the resulting golden age, etc. However, for fun and for the sake of suggesting plausible explanations for a work of fiction, perhaps the sword was looted from inside a stone tomb? Among a superstitions people, that would imply bravery on the part of the looter - a desirable trait in a leader. Later this is corrupted into him actually pulling the sword out of a block of stone -then the anvil is added, etc. And then the acquisition of Excalibur from the lake could be a garbled account of the finding of a sword which had been thrown into a lake long before, as an offering (which would make the Lady of the Lake an eccentric mudlark). I think that both of these would probably lend themselves better to a late bronze-age or iron-age setting.

As I said, highly improbable, but possibly ok for a story: "First he steals a sword from the dead, then from the gods themselves! Will this man stop at nothing? To find out, read the next exciting parchment roll..."

Edit: hmm - on reflection, I think a certain Mr R E Howard beat me to it

In the Volsunga saga Odin enters a hall and plunges the sword Gram into a tree which only Sigmund can pull out. http://www.sacred-texts.com/neu/vlsng/vlsng05.htm

Len
That's a good find. I think that would be 12th/13th century wouldn't it?
I'm pretty sure I've seen it written that Odin pierced his side with a spear, then hung himself from the boughs of a tree (arms outstretched like on a crucifix) and died, then the secrets of the universe were revealed to him. Not sure how old that story is!

Benjamin Thorpe translation:
I know that I hung on a wind-rocked tree,
nine whole nights, with a spear wounded,
and to Odin offered, myself to myself;
on that tree, of which no one knows
from what root it springs.
Bread no one gave me, nor a horn of drink,
downward I peered,
to runes applied myself, wailing learnt them,
then fell down thence.