water lilliy identification

I have a couple of lillies in my pond which i split up last year. I need to find out what type it is. The plant in question is very similar if not identical to Nuphar lutea. The only difference being Nuphar lutea has 20-30cm pads. My plant has 8-10 cm pads. I am certain it is a UK native plant as i took the original cutting from a pond in kielder forest near the reservoir. I am involved with a group who are developing a fishing lake in the local park and would like to introduce the lillies to The lake.

 

You have not given us much to go on. A photo of the flower and leaves etc would help.