It would be useful to know more about that:

How exactly is the compositional analysis carried out? What criteria is used? Is the work carried out by central government, an agency, or by individual boroughs/counties? If each borough does its own analysis how can we be sure that all boroughs use exactly the same methods? What is the agreed methodology? For what period is the research carried out, and is the analysis done for the same calendar weeks/months for every location? (could be important as some waste is seasonal). How is Lewisham's incinerated waste counted in the analysis?