Good stuff. you're lucky to have this stuff around locally. if it was me i would be going for it and digging stuff up all year round, during the winter months i would be trying to dig with as much root as possible. in spring i would be a bit more aggressive. but thats just me, if i had the opportunity. in South London i would probably get away with it if i donned a high vis jacket, then maybe i could say im working for the council or something
walk into the park with a spade and loppers around here, you'll probably be reported and arrested