Hi Coeur de Chene
Thank you for the pics. Two things spring to mind on seeing them. One is that the hedges are still very small, so several years off being layable. Laying is a method of repairing a gappy hedge, or thickening it up at the bottom, and yours looks fine. It does look ideal for trimming as an A shape. The A shape, as well as letting light get to the bottom branches so they grow and aren't shaded out, provides more animal etc cover underneath. I hate when hedges are flailed so they look ripped and broken. Is there any way you can get them properly trimmed rather than flailed? Even a good solid hedge trimmer of the sort you would use in a big garden is a possibility - a bit heavy and tedious, but you would get to know your hedge intimately while you were doing it
The second thing is a psychological one. On the field side, the longer grass and flowers could be said to be scruffy, and people like neat and tidy. You want scruffy to give the best habitat. A compromise needs to be reached. One thing we do (and it's no longer a lot of work as we have acquired a lawn tractor, instead of using a walk-behind lawn mower) Is to keep a wide strip along the hedge mown. This can be as far out as you want, but by keeping it straight-edged and short, you are demarcating the edge of the hedge, which of course includes the scruffy grassy bit as part of the corridor. This will provide a visual clue to the fact that your hedges are managed, and the scruffy bits are meant to be there. It also makes a path so you can walk around your perimeter comfortably.
Whatever you do to keep a hedge under control, whenever you first do it, it does look awful, totally ravaged. But it's a living thing and will soon be sprouting new shoots beyond its A, but will be nice and solid underneath, with good protection for nesting and roosting birds.
Apart from the blackthorn, which is an abomination to me
, the other hedge plants you have are fine. I'm not sure that laying oak would work, and elder is not a good hedge plant, it soon shades out other species to either side, doesn't lay and dies off young so leaves a big gap. Brambles too tend to get out of hand very quickly as the canes they grow can be 2 or 3 metres long in a few months. We keep a separate bramble thicket which isn't part of a hedgerow, but provides wonderful wildlife cover and tasty fruit. Hawthorn is the traditional hedge plant - lays well, is thorny, grows strongly and is nibbleable by livestock. Oak we would leave as standards, but you have plenty of mature trees, and oak responds to coppicing/pollarding ie trimming, very well, as does ash. Hazel will lay or be trimmed and forms a nice solid framework, and honeysuckle and roses are gorgeous. You might find that if you are trimming your hedges regularly the briars and honeysuckle die out, as they like to have long stems to flower on, so perhaps protect those as you trim.
Overall, from the pictures, my advice would be to cut in the A shape for many years, until the hedge becomes gappy, then grow it tall for a couple of years so you can lay it, and start again with your A. Keep the edges of your wildflower bit neatly trimmed, and explain to your neighbours that the grassy part is as much a part of the hedge as the hedge itself. Promise them a good laugh at your expense if it doesn't work but be firm and decisive about what you're doing.