Well; this is extremely embarrassing! Rather than "deffo not JKW" (as per post 6 Apr), I now have to say, very humbled and contrite, it is almost certainly JKW - actually deffo JKW.
I have never considered myself to be a gullible person, but re-appraisal may be required!
There I was, prepared to help pull a bit of early H Balsam growth, amongst other tasks, looking at a smattering of leafy growth a few inches high (with none of those distinctive fat JKW shoots) and being told by my long-since horti-trained friend that it had been identified as H Balsam.
It dawned on me eventually after some more web searches: wish I'd done a search for pics of HB v JKW 'roots' on the web before posting on 6 Apr!
Mystery over and am awaiting 'explanation' from my friend,
So thank you fellow members for pointing me in the right direction.
Now, how do I get this thread deleted for all time so that I am not constantly reminded of my embarrassment?