The fishmonger your mother trusts

Three shops on one street sell the same salted fish at the same price. Two days before Egypt's spring holiday the queue is outside one of them, and the other two are quiet.

Ask anybody in the queue why this door and the answer is never about the fish. The family has bought from him for years. The grandmother used to. Somebody knows his uncle. The man himself does nothing that a marketer would recognise as marketing, and has not needed to since the parents of the people queueing were children.

There is a reason the loyalty is that hard. In a category where a bad batch can put a household in hospital, nobody experiments on a holiday table with twelve people around it. Getting it wrong ruins the table in front of the entire family, and the blame lands on whoever chose the new shop.

So the brand here is a surname, and the trust is inherited rather than earned. A newcomer with a cleaner counter, better curing and a lower price can trade beside that queue for three seasons and take nothing from it, because the purchase is being made on somebody else's behalf, and the person making it has no appetite to be the one who got it wrong.

Which is the tell I keep taking out of streets like this one. The only door into an inherited category is one person inside the household who tries the thing and then says so, at the table, in front of everybody who was waiting to see whether she would.

One aunt is a smaller audience than any media plan would accept. Here she is the whole plan.