Thanks to Corion and tybalt89 for their answers - I was nearly there with the former's suggestion with my playing but the latter suggestion would never have crossed my mind as it ('normal' programming language-wise) looks like a completely foreign language - shades of using APL in my past!!!
BTW when I said that it threw our system's operation, it wasn't as bad as that (we are testing changes on a non-live system) but it threw our development/testing environment because we couldn't even get it to start due to the non-interpretation of the new script with the Perl version being used. We do know what we are doing.
Again many thanks for the assistance.
ADB
Comment on Re: Experimental push on scalar now forbidden
"BTW: since I have no access to 5.24 it'll be nice to know what prototype 'CORE::push' returns."
$ perl -v | head -2 | tail -1
This is perl 5, version 24, subversion 0 (v5.24.0) built for darwin-th
+read-multi-2level
$ perl -le 'print prototype "CORE::push"'
\@@