Birds nest but which bird?

I found this nest lying on the ground last week at the Sanctuary Ponds. It looked like an oblong  ball of grass but on picking it up I could see it was flat on one side, and there was a very small hole at one end. I put my fingers in and felt around the bottom and there were feathers there but no dead chicks so that was good.
There were many feathers woven into the nest which measures roughly 20cm x 40cm but very loosely woven so looks much bigger.Hoping someone can tell me which bird occupied it.
I did look up a website about nests. Something I hadn't thought about was that we tidy our gardens so much these days there is no nesting material for birds. To help we should leave lots of material in the garden or provide string, yarn and a variety of items on a rack where they can come and pull them out and use them.
This nest will go back to where I got it now I have got my blip.