[quote][/quote]You're assuming the deer won't eat the coppiced regrowth of your hedge (Hazel shoots are a favourite deer hors d'ouevres) , in which case you'd need another hedge to protect it, and another hedge to protect that one, and another, and be the time you've finished you've just got a large free-range deer park, fed on a diet of wholesome organic hedge.
Haha! Point taken nice idea, but 20years might be a bit too long too wait!