Thanks for your advice, I will get some smaller holed haynets and split the hay between them because at the moment she mainly has the ones with the larger holes.
This morning leading her to the field I managed to keep her in check by holding her leadrope right where it clips to her head...
My 14yr old mare is extremely greedy. She is 16.3hh and the vet has said she is overweight so I feed her hay now instead of haylege and she only has a small handful of hard feed (happy hoof) in the evening. However, whenever she can get extra food she will (i.e pinching haylege out of the mouth...