in reply to
Compelling arguments urgently required
Well theres a few things I can recommend. Ignore or use as you see fit :)
1) Features, advantages, benefits
How does Perl feature in your companys' work, the advantages of using Perl (cost of tool, time to prototype, difficulty of other languages) in your work and the benefits Perl provides (slightly different to advantages).
2) Give a very short case study of how Perl has saved money in your organisation (no more than 2-3 paragraphs at the very most).
3) Compare the use of Perl in your work with another tool.
Something like..... I do this in Perl, to do it in Java would take x. This means that I save, on average, £mega with every project.
If you think about it for long enough you should be able to find 4-5 examples of where you can champion Perl. Don't provide those but have them on standby in case he asks for more details (so you look prepared ;P).