Thanks to Scottish Skier for pointing me in the direction of an independence poll from a couple of weeks ago that is so obscure that it doesn’t even appear on Wikipedia’s list of polls. I might add it to the list myself if nobody else does. It was conducted by Stack Data, which is a “trading brand of Hanbury Strategy”, and thus very much associated with the anti-independence campaign.
Should Scotland be an independent country? (Stack Data)
Yes 50%
No 50%
Even with Don’t Knows included it’s level-pegging (48-48), so this rather helpfully breaks the little sequence of No-majority polls from before the Holyrood election. The fieldwork dates precede the ComRes / Scotsman poll, which means it was probably the first post-election independence poll. The bad news, though, is that the ComRes numbers I took from Wikipedia earlier weren’t totally accurate – the No figure before Don’t Knows were excluded was understated by 2%.