Confidence: I'm as sure as I can be.
Notes: Bluebells are easy to tell apart if one looks at the detail. The classic English Bluebell, H. non-scripta, has the tip of the flowering spike slightly drooping over and the flowers all on one side of the spike. The sides of the flower tube are parallel for most of it’s length with the tips strongly reflexed (ie turned back on themselves) with cream anthers. The leaves are narrow (7-15mm).
The Spanish Bluebell, H. hispanica has a flower spike which points straight up with the flowers all round it. The flowers are bell-shaped flower, becoming saucer shaped with age, with absolutely no curving of the tips, anthers are the same colour as the flower (which may be variable). Leaves broad (10-35mm).
The hybrid, H. x massartiana has the general spike shape and flowers are bell shaped, but with tips curved back to some degree, not as much as in H. hon-scripta. Anthers normally blue, but sometimes cream (no help there then). Leaves broad (10-30mm). It is very fertile so back-crossing is common, giving a wide array of variation from the two extremes of the species.