There are some figures here. Note is is banned in Europe.

http://www.uky.edu/Ag/Horticulture/masabni/Publications/HO-83.pdf

not sure if it is allowed in the uk for the amateur gardeners. Check with the RHS or Defra to be on the safe side. lots of products containing it were withdrawn from sale under EU directives.

Yes it has been withdrawn but I understood Ray to mean that he already had some?