"There is only a short time period in which it can be done".
This is not the case. Although hedge -cutting can resume on 1 September, DEFRA advise that where possible to trim hedges in January or February to preserve habitat and food for wildlife.
Unfortunately, this advice is largely ignored (certainly in this area). Many British birds are in decline, and it's sad to see the devastated hedgerows - brutally hacked both sides and top.
As part of the 'Single Farm Payment' subsidy scheme, farmers are required to maintain hedges, but all too often it's taken to extremes. There are moves to introduce different hedgerow management, where certain hedges are cut either bi-annually (some berries only form in the second year), or left for several years.
Of course, roads and tracks need to be clear, but maybe in the future many of our hedgerows will be spared this butchery - it's just mindless vandalism of the countryside.