Beautiful birds you have there
@Ribh ! I think more hedgerows have disappeared through neglect than active removal - if they're not maintained or grazed they turn into a line of trees or a bramble/braken/scrub patch. But fortunately they can be revived if they haven't gone too far, so it's not the end of the world if they've been left for 5 years or so

Thereafter it gets trickier. I'm not sure much is added after, say, 5 years' proper maintenance. What exactly makes a 'heritage' hedge in NG's view, other than an occasional very old tree (one that was allowed to grow up) in the middle of it?