...PS Does excreta ever actually go off I wonder 
Well it certainly becomes odourless after a while, and eventually, given the right conditions, turns into
this.
It's one of the ways that ancient civilisations eating habits have been deduced, and also any internal parasites they may have had as the eggs of the little critters are sometimes present and identifiable.
But on the constipation malarkey, I suffered from a bout a few years ago, not helped by also having some Michael Miles.
Not sure which was cause or which was effect.
My GP at the time (in fact a locum and not my normal one) promptly and with little warning stuck his gloved finger up ( it's very much a one-way street for me so that was agony) and wiggled it around but couldn't really find anything or give much advice other than try a change of diet.
I stopped eating bread and it improved the situation no end for me and I haven't suffered for a good few years now and am reasonably regular ie every day with little effort. I also cut out breakfast cereals and a lot of fruit like Bananas (they give me a migraine anyway), surprising in that normally people would say you must eat these things to go regular. I now usually just have two olive oil fried eggs in the morning on a couple of toasted potato cakes with a few diced and microwaved mushrooms on top and a flagon of milky tea. It all seems to work like a plunger....
Another cause though, often overlooked, is it can be stress related.
