Being a native of the New Zealand and a sub arctic plant it will survive the winters in Hertfordshire fine - needs moist conditions like a stream bank.

Or gunnera magellanica. I've had this for several years, and it has sailed though every winter. I grow it in aquatic compost in a planting basket, half submerged at the side of my pond. No feeding, just a trim and tidy in early spring

Moon Grower,
Thank you and I shall definitely be acquiring one soon.

Andrewr,
I have just looked up this gunnera macellanica and it looks suspiciously like the plant I was trying to eradicate last year that was so invasive under the weeping pear. I kept some in a small pot and it will probably look good if I do as you have done, so thank you for suggesting that.
Linmar

Andrewr,
Could you tell me please does G.Magellanica have red stalks?

Linmar - the creeping stems on mine are green, but I have seen pictures of some with red tints to the stems. The little flowers are a browny-red colour. Is that what you mean?

Andrewr
my plant is about 3" tall & did have beetroot red stems; I can see it from patio door & notice now stems looking more black. The leaves look identical to g.m. whatever it is had spread a lot under a weeping pear. No flowers ever! I thought possibly because in shade. I shall keep the pot in the sun and see whether it eventually flowers and keep you advised.

Andrewr - I would hate to mislead you! The plant still has red stems they just looked darker the other day - I think its grown about 3/4" since yesterday!

I've not come across one with red stems, so I'm not sure which species you have

Could you put a photo up Linmar...

Moon grower
I have tried putting photos on a few times but my comp. just not allowing it to happen. I have app.with dentist shortly so will have another go this afternoon.
I probably need to buy some new equipment!