Lovely photo and shows coppicing better than I could. 
I'm guessing that the area is no longer coppiced? Most of the clumps look quite mature. Though I believe that trees differ in the length they are best left between cutting eg Oak (50 years), Sweet Chestnut (15-20 years), Hazel (7 years).
I'll just coppice the quote if you don't mind.
It occurs to me that Oak, Sweet Chestnut and Hazel would have been particularly useful to keep, because they had secondary crop of nuts, chestnuts and acorns.
No, the area is no longer coppiced, (although work is talked about and being argued about at the moment, not a subject for this forum) that is why I referred to it as lapsed coppice. We should admire what our ancestors learn and achieved and if we don't shortly buck up our ideas, we may have to re-learn this old knowledge.