Several come to mind. One of the campanulas, Borage, comfrey, Scrophularia or even a salvia.
are the leaves prickly/stiff hairs? are they scented?

Thank you for your reply I will ask, my friend is another "site friend" I thought it may have been one of the small wild teasels. Its had me puzzled it looks familiar and yet ?

Teasels have raised spikes in the leaf which this doesn't have. It looks so familiar to me too.
does the leaf have 2 small leaflets towards its base?

Yes it does have the two small leaflets and not hairy

This looks like a verbascum I have in the garden.

Looks a bit like omphalodes

Thank you for your suggestions,its the two tiny leaves at the bottom of the stem that is causing the ? Think it may be a weed!

assuming you have normal sized hands that leaf is huge. My omphaloides has small leaves.

I have had a look at Dipsacus pilosus [small teasel] and it could well be that. it grows well in ditches and damp alkaline soils. does that sort of fit with your friend's garden?
I have been checking the wild flowers and Verbascums don't have the leaflets. so I suspect Small teasel it is.
weed/wild flower/desirable plant its what you want it to be :o)

Not my hand but think it is normal, small teasel is what I thought first, but others differed. Garden is enclosed with lots of vegetation in south london, Thank you for your help, will wait and see later what it does, I will let you know when/if we know,

I always like to let unknown plants to flower before pulling them up. It could be worth the wait and if you find its a weed then nothing's lost.