Your heart sinks when you push the garden fork into the ground and find the clay that lies not far from the surface of the ground.
It is either rock hard which no amount of jumping on the fork will penetrate or it sticks to the fork and your boots.
Looking along the rough furrows of a field you could think that nothing can grow in such heavy sticky stuff but by the skill of generations of farmers, come spring, this heavy, ridged field will be a mass of green shoots and then a field of golden corn. Hard won farm land so vulnerable to the weather's fickle changes, to fire, to vandals and even to slugs.
Compared nationally the soil locally is rated No 3, the lowest of three grades.
34 acres can be ploughed in a day now by tractor, 30 acres in a week by horse and plough
In 2007 there was so much rain that the beautiful green heavy ears of wheat turned black and all the farmer's hard work was wasted. I can't imagine how he felt but I could have wept.
Clay for bricks and tiles was dug from pits at Cupid Green and High Street Green.
When the Grand Union Canal was dug opening up the London market the narrow boats brought back dung, road sweepings and night soil which further added to the fertility of the soil.
Now it is 'green waste' from the Cupid Green Recycling Depot that goes back to enrich the soil somewhere, but not locally.
It was the fertility of this soil that generated the riches to build St Mary's Church. Hertfordshire was known as the Breadbasket of London.