triffid

I'm not at all sure about this but if I were to guess I'd say it was an Echium Pininana.

Yes it looks like an Echium Pininana. They are a biennial, the leaves grow one year and the huge purple flower spike will grow next year( it may be a white flower spike if it is the variety called 'Snow Tower'. They will get up to about 12ft tall!! They do have a tendency to self seed everywhere as well. I would do some research on the internet, you may need to protect it from harsh, long frosts.

I don't think I've seen that plant before - looks amazing!

Great, isn't it? What a size!

Biennial????? They grow to that size in one year???? Please put up a picture of the flower next year, Muffsea, I would love to see it.

I thought I'd seen this one before ! If you type the name into the search on this site it comes up with Sandras photo's of this plant.
I can see a spot of transplanting coming on lol.

If you are near Kelly's Resort Hotel in Rosslare, Co. Wexford, the Echium is a dominant feature in the gardens. When it flowers, it can grow up to 3m tall and then dies back. If the seeds find cultivated ground, they grow readily and start the 3 year cycle. They are reasonably hardy and can be damaged by severe frost. If you transplant them they will readily wilt for 3 days but will recover quickly. Their seedlings can be identified by black spots on the leaves. I have an expert to hand this evening! Hope this helps!

Yes, this variety is a biennial! It is known as 'Pride of Madiera' which gives an idea of its usual growing climate. There are other varieties, Echium Wildpretti which has a smaller flower spike and is pink, not as hardy as 'pininana'. The perennial variety is called Echium Candicans aka 'fatsoum'. That is a smaller plant and the flower spike is bluer than pininana. They are related to our native echium vulgare (vipers bugloss). I live on the Isle of Wight and the local Botanical Gardens is well known for the Echiums. I have a collection although I lost most of them in the frosts last year so I am starting again with Pininana, purple and Snow tower which is white.
If you didn't plant it in your garden, there must be the plant that let the seeds out nearby in your neighbourhood??

Many thanks for your respones, I am happy now that I know what it is. Will look out for new plants in the coming years.