It was such a good plan.
Instead I found myself picking my way along heavily-puddled Trumpington Street, looking for somewhere to shelter from rain and boredom. The church of Little St Mary's looked promising from the outside, but inside seemed very modern, very sterile. The glass inner doors featured some words which I've since placed as being Herbert's:
A man that looks on glass
On it may stay his eye.
Or, if he pleaseth, thro’ it pass,
And then the heaven espy.
but what I saw through the glass (not even particularly darkly) didn't tempt me to pass thro' it.
A little further on, however, I found St Botolph's, which was much more my cup of tea. Dark and gloomy, full of wood and the weight of years. I duly admired the 17th century font cover in all its recently-restored original glory, and the wooden screens decorated with simple iconic artwork and an almost-unreadable Hail Mary in faded gilt gothic lettering.
The Saint himself, whom I confess I'd never heard of before, is a patron saint of travellers; churches dedicated to him are apparently often found near the gates of cities. I hadn't realised where Cambridge's gates were before, but found that I was in fact near the site of the mediæval city's South (or Trumpington) gate, the gate by which people who had journeyed from London would enter the city. I was also intrigued to discover that Boston is named for the Saint, originally being "Botolph's Town". That's Boston, Lincs., of course, the famous English town after which I believe an American city is named.
There was a small bookcase in the church containing second-hand books for 'sale' (a box was provided for donations), the funds to go towards some restoration project or other. You'd have to sell a lot of 20p and 50p books (including various books about dBase III, and the seminal 80s publication "How to win at Pacman" -- très Cambridge!) to get anywhere near the amount presumably required to restore a church, let alone the £19m being spent on the renovation of the Fitz's courtyard just down the road, but I guess every little helps.
The brief respite from the rain helped a little, too.