Titmarsh don't get me started LMAO him and his filthy novels
A crock of shit, is indeed a reference to Alan Titchmarshe's books.
The word crockery arose in the eighteenth century from the now-obsolete crocker, or "potter," which in turn came from the Old English croc, "pot or vessel."
So way back before the WC *Water Closet" we used to have to go to the bottom of the garden to take a dump.
You either crapped on the floor of a small shed and would leave it there for the "night Soil man" to come and magically make it disappear, ready for you to lay a new one for him, the next day.
Either that or you had a "long drop" where you would drop your load, until the pit filled up and you dug a new one.
Those long cold winter nights, where all you had on, was your night shirt, could see you with nothing more than a "thumb and a half a walnut", where your once proud family jewels used to be!
So many people would say "sod that for a game of soldiers" and reach for the "Guzunder" so called because it "Guz (goes) under the bed" AKA a chamber pot.
Such a pot was often made of crockery although some were metal.
So a crock of shit is something that went under the bed just in case you should need to send a brown parcel in the night.
I imagine for the most part, people would try to avoid the night time bowel movement as it would probably leave a bit of a tang in one boudoir!
A midnight pee is more acceptable and more likely.
So if something is a crock of shit, it means it is full of shit, just like a guzunder might be, should you be suffering from a bout of Montezuma Revenge AKA a dose of the trots.
You did ask!
Interesting fact
The Rhubarb Triangle is a 9-square-mile (23 km2) area of West Yorkshire, England between Wakefield, Morley and Rothwell famous for producing early forced rhubarb. It includes Kirkhamgate, East Ardsley, Stanley, Lofthouse and Carlton.
The reason why the rhubarb grows so well is the locally rich soil.
Yup you got it - the rhubarb triangle is the area where they used to spread the night soil!
So it you hear someone saying "This rhubarb crumble is the shit" you'll no they aint far wrong!
You can go and watch the rhubarb in the forcing sheds, which are lit by candle light, if you are quiet and listen carefully, you can actually heard the rhubarb "Creaking" as it grows!