Could it be a teasle? If so, you can buy them from the Garden Centre as 'friendly' garden plants, but if they seed around too much then they become 'foes'. Good for the birds such as goldfinch.

my first thought was dock/sorrel. Doesn't teasel have spines on the leaf surface?
if it is dock/sorrel then it is a native but also a common garden weed.

Don't dock and sorrel have smooth leave edges though? I wondered about comfrey?

Looks like one of the comfreys, but not the native one because the leaves don't extend down the leaf stalk. Perhaps grow one on to flowering to make a proper ident.

so the general consensus is that its probably ok it has seeded around a lot but never saw it flower it has no distinctive scent the reason its in pots is my wife dug it up and in case it was something nice we kept it in pots

its not teasle, sorrel, dock or comfrey i will just wait i guess see if it flowers but has very big leaves if given right conditions

could it be Burdock? the flowers are insignificant and the seed spreads easily.

I have no idea what it is, but I do like the excitement of 'wait and see' although sometimes it's a big disappointment!

i have solved the mystery of my invader it is TELEKIA it was being sold in ripley plant fair in surrey at £7 a plant! i must of collected seed somewhere and planted it... strange thing is it never flowered or i would noticed it as its 4ft and i have a small garden and now its everywhere in all different spots ..........strange unless i planted it in different locations my memory is not what it was being in my 50s its growing habit seems to be fussy as it likes wet soil,sun,shade,well drained, not exposed, not full sun not dry and not too well drained ?????? wow!

Just looked it up (never having heard of it). Said it was wonderful up to July and a ratty brown edged heap from August onwards. It will be interesting to see what happens when it flowers.