Tackling Japanese Knotweed - eek!

I don't want to tell anyone official, and cause trouble - the customer and her farmer neighbour get on very well, and they have just kept cutting back encroaching bits over the years, and I think she'd prefer to carry on in the same way....... I was just hoping there was a quicker way - but there isn't!

I have tried to ring someone I used to know who works for another council down south, to see what he thought, but "this person's phone is currently not available, please try later"

 

We had it at work on an adjoining plot. Its roots can attack and penetrate concrete foundations. Someone said its not notifiable, however it is an offence I'm told, to propogate it or remove it to a different location. We had to install a six metre deep steel sheet pile wall to prevent it spreading onto our land and any contaminated soil needed a waste transfer note and had to be taken away be a specialist site where it is buried more than five meteres below ground. Nasty plant.