Nick & Jeff, thanks a lot. Well, because you say vinegar only "burns"
that which it comes into contact with and it doesn't infiltrate the
grass systemically (to reach the roots to deal with them as well) it
would be a completely bloody foolish of me to use it. Planting a fairly
large rock garden with dozens of heathers and ornamental grasses
gathered and ordered from all over the place, only to have grass
shooting up through it all a couple of months down the line, if not
earlier, would be madness.

Thanks a lot.

Eddy.