And we are assuming that Fred was retiring in Feet of Clay due to old age. This is not necessarily so. After all he was planning to buy a farm and settle down to that. In Snuff there is an ex policeman who has retired and bought a pub. He doesn't seem particularly old.
Sharlene and I were talking about this the other day and she wondered if Fred wasn't retiring due to all the different species joining the Watch. Fred is one of nature's natural bigots I think.
"Goodness is about what you do. Not what you pray to."