Thank you for the replies. Its the adjacent that seems unclear. The trees were planted along the inside of the old fence and it was shorter than 2m but higher than 1m as it was taller than my kids who are around 1.2m. The grass verge is narrow around about 0.8m wide.
I think for us it just seems strange for them to send us a letter but say that we can leave it unless they have another enquiry.
Thanks again