Hi Pete
I live in Essex in one of the driest parts of the country, I have an allotment on which I have limited time to tend.. when setting it up 4years ago my attention was taken by the method of gardening by the Head Gardener at Tresillion House in Cornwall, his name is John Harris. He avocates digging trenches under your crops, filling them with good rotted organic material, refilling, this then captures the moisture that is drawn up by the first phases of the moon, and the falling rain, when we get it:) Quite opposite to Charles method however the deep dug trench lasts for 4years… Worth a read… It does work.
This year I have read about Charles method and my interest has been similarly taken so I have created raised beds at my allotment and filled 18inches will good rooted organic material and topped up the rest of the raised bed with soil. With a view to topping with up per Charle’s method when appropriate for the beds, my goal is to have produce all year.
I still have my Runner Beans over a Deep trench and my Potatoes…. I do water a bit but nothing like my neighbouring allotment holders and the soil stays moist right where the roots of the plants are. Good luck Kah