What to do with an escape artist?

[stormox]

I have the mare I ride and a 14.2 pony companion. Both 8 years old and have lived together since they were 4.
Both are happy to go out in their field or ride out on their own.
But the pony has started escaping - takes no notice of electric fencing, pushes it over, walks through it or somehow grovels under.
Jumps over ditches, pushes through hedges, jumps post and rails.
She does it on her own or if shes with.her friend ( the other mare stays behind on her own).
She does it if theres hay in the field, or grass - its not like shes going out for food.
So this past week she has had to stand in her stable, while the other mare enjoys the field.
I was wondering if anyone had any experience of tethering? Or hobbles?
I know that sounds awful but I hate her standing in a stable the whole time with just a daily lead out.
Thank you.

 

[Kaylum]

Heras fencing is what we use they can't jump it it's too high.

 

[stormox]

Heras fencing is what we use they can't jump it it's too high.

It would be awfully expensive round a 2 acre field, and I dont think the field owner would be too happy unfortunately.

 

[be positive]

A double electric fence, so one inside far enough apart so she cannot jump, then clip her chest if she uses that to walk through, I attached a small bit of fencing to the breaststraps straps of one pony and later a bit going through his flymask so he got a proper shock, he only tried the once with each method but he was just trying to push through jumping was not an option he considered.

The double fencing worked for another most of the time but he was always an escape artist so we went through most things over the years.