We've had this a few days ago. It's figwort, scrophularia nodosa. Not poisonous. Once used, according to Culpeper, for the treatment of piles, and no less effectual for 'other knobs, kernels, bunches or wens growing in the flesh wheresoever'!!!
For those of you who haven't a copy of Culpeper's Complete Herbal, do get one, it's hugely enlightening, and sometimes highly amusing.

Wow, thanks, Worthy! (I had a feeling you would probably know!...)And I love the Culpeper reference...

I'm sorry, folks, that I missed the previous question on this plant, apparently asked "a few days ago", and thus repeated the query to you all. Good to know the answer, though...

The pale leafed one with it is dog's mercury, a member of the euphorbiaceae. It is a powerful emetic (another Culpeper plant, as it happens) and really rather poisonous. For some reason dogs seem attracted to it, sometimes in preference to grass, and it works very well, provoking the reaction the dog wants, but doesn't do the dog much good. Just to bear in mind. Wear gloves, just in case

Thanks Worthy, for the warning, but I think the pale leaves you are referring to in this instance are part of the hydrangea shrub within which the figwort has - regrettably - sprung up - the hydrangea isn't flowering this year presumably because I over-pruned it last time around (I don't really like them but they grow well here so we all have them!) or perhaps because it seems to have developed some sort of 'leaf curl'?

By the way, does anyone know why photos that look OK on one's computer turn out sideways or upside down on this site? !!! (see no.2 above) I've tried to correct this but without success: perhaps when they're upside down it's in compliment to our down-under, Australian, members???!