Weed dilemma

if you like it and you can see the benefit to the wildlife I'd leave it. I would certainly have a go at a proper id of it. if you havent got a wildflower book you can always borrow one from the local library. [The collins fieldguides are good ones.]

Thank you Seaburngirl. I've got a wildflower book but I think its still in the loft since we moved here 8 years ago!! I think I'll leave the weed until the seeds set and then deal with it.

If the plant is as tall or taller than you, Cammomile, then do not touch it until you have it properly id'd. From your description this plant could be Giant Hogweed. The sap of this weed will burn your skin and can be very nasty.
We have a lot of this in my locality and it has just finished flowering.

If it 'is' Giant Hogweed and it 'is' on your ground you have a duty to destroy as it is viewed as a noxious weed.

Apart from Moon growers wise words, and plants of similar ilk, think about the benefit all those insects are having in the remainder of your garden, and others.
In fact, if they had destroyed a similar plant that was growing in their garden, maybe you would not be receiving those insects in yours.
A simple rule to live by:
KEEP IF YOU CAN.
Of course, that doesn't mean that you cannot move it to a more suitable position.

Fingers crossed it is a different plant

I am pretty sure it's not giant hogweed - I have had first hand knowledge of that in a friend's garden and it is different. I don't think it's hemlock as the leaves are different - larger and hairier. Unfortunately I haven't as yet got a camera so until then I shall just have to search 'tinternet - I shall let you know and thanks.

Good luck I look forward to hearing what it is.