Roy,
This is from the job evaluation handbook;

For evaluation purposes, the job to be described consists of:
• Those duties actually carried out by individual jobholder(s). The last year is generally a good
guide on what should be taken into account as part of the job. The job is not an amalgam of
what the jobholder might be required to do in other circumstances, nor of what the jobholder's
colleagues do.

We don't actually work shift patterns at the moment, so should what I might do in the future be presented to the matching panel?
Should therefore my current job description change?