Thanks for your help, both people.

I found that by using a very well-publicised short sub, and deleting my own efforts, I was able to build the query-string and utilise LWP to make the post. I think the problem is that I'm still very 'green' when it comes to perl. The way I got around it was to use, virtually unchanged, a sub called do_POST (from perldoc.org), passing it a URL and references to the constructed hash and header objects.

Again, many thanks for your help.