In article ,
Roger Tonkin wrote:

What no one seems to have mentioned is the location of a hedge. In this
day and age, when people have cars and often tend to dump rubbish/garden
waste by the road side, such a hedge would not be an ideal candidate.
Also hedges near to modernish housing estates (those with more than a
pocket hankie sized garden) will suffer from contamination(couldn't
think of a better word!) from the plethora of non-native plants/trees
sold these days.

I did! And it's not just modernish estates and non-native plants;
I might have been misremembering about 9 species, but a recheck
through that list confirmed at least 6 for a 70-year old hedge.
And the list specifically excludes non-native plants, including
Japanese privet (the usual hedge privet).

I would guess that only field hedges several hundred meters away from
roads, housing, bird feeding site etc are likely to show true natural
species generation.

That's a bit too restrictive. One of the main reasons that woody
shrubs establish well under suburban hedges is that their base is
often kept clear of undergrowth. A field hedge next to a road
will still have its base overgrown with grass etc., discouraging
woody plants from establishing themselves.


Regards,
Nick Maclaren.