These links will help.
Look at the colour of the pollen...Quote... "Pollen colour
The easiest way to tell the difference between native and non-native bluebells is to look at the colour of the pollen.
If it is creamy-white then the bluebell is a native. If it is any other colour, such as pale green or blue, then it is definitely not native.
When the pollen is shed, the empty anther can be a pale cream colour, so make sure you look at the most recently opened flowers at the top of the spike, to find the true colour of the pollen."
There are 3 "bluebells" now in cultivation.
1. Hyacinthoides non scripta. The true English wild bluebell.
2. Hyacinthoides hispanica. The Spanish bluebell....
3. Hyacinthoides x massartiana. This is a hybrid between the 2 others.