I wonder if its perhaps a verbascum. If so it should produce a tall yellow flower spike. Perhaps its a silly question but have you tried watering your chives? They don't usually flop over unless they are very dry.

I agree - it's a Verbascum, also known as mullein.

Thanks! That's great... In fact it's just sprouted a yellow flower just today...! re. the chives, I've been watering everything every day, though when we first moved in there was a period of five days where no-one was here, and they've not perked since then. I've cleared a lot of the dead stuff away - one just won't perk up but the other bunch is starting to come good again. Thanks for you help.