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... and the new growth starts to appear (in some cases) as early as August.
I was looking at some new ground (a country lane) on Tuesday and while it wasn't as easy to spot as Heracleum and Aegopodium, I did find new growth of Anthriscus sylvestris at a few locations.
Thanks again for useful information. Glad that my initial instinct was right!
Lat/Lng: 53.62724, -2.35275
OS grid ref: SD767145
Hedgerow along path to open farmland.