"Stewart Robert Hinsley" wrote
Presumably another garden escape, seen growing in a street in front of
an electricity substation.

http://www.stewart.hinsley.me.uk/Images/Dicot24.jpg
http://www.stewart.hinsley.me.uk/Images/Dicot25.jpg

Looks like square stems so a member of the mint family, like Agastache
urticifolia. Giant hyssop, perhaps.

--
Regards
Bob Hobden
W.of London. UK