I had the manager of Morrisons ask me once to remove my open face helmet instore as I was paying. I asked him two questions.
Question one - Can you please take me to the sign at the entrance where is clearly states that store policy requires customers to remove helmets before entering? His answer, "erm, no, we don't have one". I informed him that this is a legal requirement, and if it is not stated, I am not obligated to remove it.
Second question - If I was wearing a Burka, would you refuse to serve me? His answer "No, of course not", to which I responded "So, to clarify, you are a bigot, racist who is unaware of his job and coming up with ideas above his station? Do you really want to take this to the next level, or would you rather just apologize now and walk away?" He did.