I think its probably caper spurge, Euphorbia lathyrus, a weed plant.

How strange. The opinion was that it was a fritillary but I couldn't remember planting one in that place! Thanks for you help

Do you have a better photo of the flower?
I'm wondering if it is a Frittilary with a failed flower atop.

You could wait for it to branch a bit more and the bracts to start appearing to be sure.

Meanie, this was the clearest photo out of three shots!! I'll try to get another one, meanwhile I'll leave the plant and see how it develops.

It reminds me of Fritillary.

It does look as if something's either aborted or been damaged at the top, so no flower.

Ahaa - I did put a fritillary persica (the dark purple one) in the garden months ago - about October - but I can't remember where I put it (another 'senior' moment I'm afraid). But the tiny little white flower thing right at the end, at the top is puzzling me. Weird!!

The pic's so blurry I didn't know it was a tiny white flower! If it is, then its not caper spurge.

Does the flower look "dry"?

I'll have another look at it tomorrow and get hubby to do a better close up shot of it.

i was going to say F persica as mine is just coming into flower. they have small flowers almost white amongst really larger ones. but not too sure. the folliage looks correct. i will endeavour to take pictures tonight.

I have put a picture of mine up for you to compare it with Sheilar.

I've had a look at your pic SBG - yes, it looks like the same plant but yours is further on than mine!

i kept it in the greenhouse over the winter and only planted it out last weekend.