I followed the instructions on the website and there was an ommision which meant when the .less file is accessed, I got this error

Error Summary
HTTP Error 404.3 - Not Found
The page you are requesting cannot be served because of the extension configuration. If the page is a script, add a handler. If the file should be downloaded, add a MIME map.

The final thing you need to you in your web config file .less files to work is to add entry in

This omission on the website had me stumped for a while.