Well done Len
I was thinking Eye Bright but I just couldn't find one that looked like this.
The RHS tell me it is an escapee, cultivated Lobelia and I think I believe them.
Take a look at
Lobelia ErinusI should have just asked you six weeks ago

. Anyway, thanks for confirming my idiocy,

It is OK , I have suspected this for a long time.
I just wasn't looking for Lobelia on a forest path.
Thanks for the answer.
Colin