Sweetcorn at a no dig allotment, how it’s grown and how to see if cobs are ready

https://www.youtube.com/watch?v=5_ZpMmilH4UAn iPhone video for a change, apologies for wind noise. Filmed 15th August 2018 after a warm and dry summer. Easy to grow no dig, the only ground prep was a little-composted cow manure the previous November. The soil is heavy clay and holds moisture. Spacing is 30x30cm or 12x12in, variety is Mezdi from Bingenheimer Saatgut seeds: open pollinated biodynamic, not hybrid or super sweet. However, it keeps sweetness for 2-3 days and was Brix 16 one day after picking.