As I was planning to go to Lichfield today anyway, I decided to take my camera and see if the headstone was OK to photograph. Whilst I haven't got the photo yet, I do now know exactly where it is, and that it is legible. I will go back to Lichfield and get a photograph for you.
I was told when I telephoned this morning that the Verger would be able to point me in the right direction - WRONG

He denied all knowledge of it. However, one of the volunteers then took me to the Cathedral shop where I spoke to a lady, who said that if anyone knew where the headstone was, it would be her husband. I have just had a lovely conversation with him, and he has told me the location.
I also took the opportunity to visit the Archives and checked on the burial register for the Cathedral.
27 February 1862 - John Bennett (Vicar Choral) - abode The Close.
In the meantime, if you send me a PM with your e-mail address, I'll get the photograph (possibly tomorrow if it's not raining) and send it to you.