I think it may have been the paint fumes (we are having the front room redecorated right now - yay!)
The idea has not gone away.
It is still bubbling at the back of my consciousness, waiting to re-erupt.
But I decided to be "sensible" and try out a simpler Oki-Style pattern before throwing 2.8 metres of wool into the abyss.
So... I bought the patterns for this top and skirt:
Sherwood Fabrics (who sell the lovely green coat material) for the skirt and trousers.
And a piece each of forest green cotton lawn and (ahem) burgundy silk to make the top, twice.
Because clearly that was the only sensible thing to do with two weeks off work over Christmas and no discernible fabric stash to fall back on.