I'm sorry that your writer thinks a good smack in the supermarket would instill discipline.
I took the attitude that consistent childcare matters. I chose to have children, not fashion accessories tacked on to my life. As one who took the loss in income (then watched in terror as the mortgage interest rate rose) I am a mite tired of listening to others parade their guilt. If Diana Appleyard thinks she has got the balance of her life wrong then she must reassess her life and make whatever changes she sees fit. Some of us have never been so daft as to take a four-year-old into that sort of formal setting, and when we buried grandma this summer all her grandchildren, from six upwards, knew how to behave appropriately.