Gt Whitely Hall

[Woodytia]

That sounds like the lake I used to have access to. The man who owned the land that was essentially his back garden was resident in a large house called Pool House, he may still live there and may still be willing to let folk fish from his land, at the time you were not allowed to fish from the fields that were owned by a local farmer. It may well be that he has sold up and moved on.
If memory serves me correctly the entrance to the house was past the gatehouse on the track that leads down to the ruin of Whitley Court, I think his name was Higgins.
I'm sure this lake was probably linked in some way to the massive fountains in the grounds of Whitley Court, I remember exploring once and discovering a brick lined cavern under the dam with ancient mechanical workings in it. There was also a garden water feature set into a wall which was so clear and still you had to touch the water to see it was there. Perhaps the most evocative thing there was an old oaked beamed boathouse with wooden shingle tiles that must of served the big house. Infact it is the sort of place that could of featured in one of CY's books, it definitely had the right atmosphere.
Another place I know which was similar and is reasonably close is Ladies Pool in Blakedown, as far as I know is privately owned and possibly leased to a small syndicate.