814,
Are you applying for a new post at the same place (within the same Trust), or a new job elsewhere?
I ask because I had a friend at Addenbrookes asking for a reference a couple of months ago and the circumstances sound very similar. It transpired that the same application forms are used for internal as well as external job applications so my input wasn't required.
Otherwise your discharge docs or valedictory letter will have to do.
Good luck