any free-thinking head teachers circumvent the requirement quite skilfully, managing the ritual with little or no bowing of heads or joining of hands whilst satisfying the needs of any gullible Ofsted inspector

That's what I meant when I said "covertly evading the law", and I certainly didn't understood you to be disapproving of such actions.

An in-your-face badge like that with a slogan is one thing - but a better parallel might be badge with the Humanist Society symbol. I'd be wholly opposed to any school barring teachers frrom wearing that.