Pale yellow "wildflower" - native to Scotland?

Forgive me if this description is a little vague, you all enjoy a challenge - right? :D

I first saw this plant on the A74M (Carlisle -> Glasgow road) there are huge areas of it growing, much like a clump of Daffodil bulbs, and it seems to be able to thrive in wild couch grass infested areas. (Motorway embankments)

The plant itself looks a lot like a single stem cut from a Yellow fig leafed hollyhock;
http://www.anniesannuals.com/plants/alcea_rugosa_yellow.htm

It's about 18 inches high with the top 6 inches full of very pale yellow flowers.

It flowers end July / early August and I have never seen it thrive anywhere south of Carlisle.

I was sure this would be in a wild flower identification book I have at home, so I didn't bother snapping a picture. Well the book is either completely pants or its a foreign species introduced after 1992.

 

Oenothera biennis perhaps?

 

Good suggestion Ivory, but the flowers looked paler and the stems seemed shorter. I'm sure I would have recognized these if they were Evening Primroses as we planted several in the cutting.
Or should I get my eyes tested and drive a little slower .....

 

I would guess a Mullein. There tend to be lots around here this year-very eyecatching.