I'm aware of the NLWA's long term programme to eradicate knotweed on Pinkham Way. What is its present assessment of the problem, if indeed any problem still exists?

This request is being handled under the Environmental Information Regulations (EiR) 2004 and has been allocated the reference number 2019-05 . In response to your question:

The Authority has been managing Japanese Knotweed at the Pinkham Way site since April 2012. The site is periodically inspected and when the plant is identified it is treated with an appropriate herbicide. The intention is to prevent the spread of the plant to neighbouring properties and to restrict its growth within the site. The Authority last formally surveyed the site in 2012 (see attached map) and since then the extent of growth has been observed to have reduced. 

However, it is anticipated that the management programme for Japanese Knotweed on the Pinkham Way site will continue for the foreseeable future as the Japanese Knotweed plant may remain dormant within the soil for many years before re-emerging.