Looks very much like a nicely grown Fireweed. Chamerion angustifolium or Rose Bay Willow Herb, but don't quote me.

Yes it does look like that Owdboggy, I've uploaded another pic from above, to see if that makes any difference.. anyway, technically it's a weed? I've looked fireweed up on Wiki and I remember them from waste grounds years ago in Sheffield. Can't say I like them much.

It's a weed and one you do not want in your garden...

The flower bud does not look right for RB Willowherb, but regardless, it still looks like a nasty weed!

Take it back!......

As I said, don't quote me. Not sure it is Fire weed now, looking at that bud.

If it is in the ground I suspect what has happened is your erigeron and this was also in the pot as a seed.

I only buy compost etc from Wyevale now as it is prohibitively expensive for plants plus we have a brilliant local garden centre which is incredibly cheap, sells plug plants at 45p and gives away free plants on trolleys which may look a bit sad but which do really well with tlc.

I remember years ago Cammomile we but a sad looking Rhododendron for £1 from a nursery near Inverewe Gardens with some tlc it grew into a splendid shrub and is still happily living in our garden to this day!

Cheers every one. Actually I called in Wyevale this afternoon and found a solitary pot in the Sale section which said erigeron on it but was obviously the same plant as in the pic. The manager said to bring it in and i can swap it, no explanation as to what could have happened though. By the way, Moon grower, there was no erigeron, just the weed!

That is the challenge when you but from a GC

I'd have let the flower open before taking it back so you'd know for sure what it is. Pretty certain its not willowherb, The flower bud is quite wrong for that.
Could it possibly be an eryngium that hasn't developed toothed leaves?

I agree it's not a willowherb of any kind, not sure what it is but I'm fairly sure it's Daisy family, Asteraceae, and I suspect that it is an Erigeron - there are hundreds, which one were you expecting? It's good that the nursery are willing to exchange without question though.

hi, I think it could be a variety of Erigeron glaucus, Derek.

What did the nursery say when you took it back?

No I didn't take it back, just told the man in charge, I don't think I'll bother taking it back, not worth the effort. I'll just see what it is when it flowers and then bung it in the bin if it's not nice. Wish I had the erigeron though, I quite like it.

I think I might be able to split mine of you want a bit - PM me

Oh that's such a nice thought Steragram but please don't go to any trouble, I can probably pick one up from a roadside stall on my travels. There are lots of houses that put plants out (usually for one or two pounds) and you put the money in a "trust" box, got quite a few plants that way ! But thank you very much for the kind offer..