As well as containing the prime meat — usually imported from Japan — the snack also features other pricey ingredients.

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It has porcini and truffle butter, gold mustard mayonnaise, mushrooms, rocket and braised onions.

Truffle is one of the most expensive ingredients going, costing between 65p and £1 for a single gram.

A similar roast beef and horseradish mayo sarnie from Marks & Spencer costs just £4.

Also available at the Harrods food hall in Knightsbridge, West London, are wagyu katso “Sandos” — measuring just four by three inches.

They contain deep-fried wagyu ribeye with mushroom ketchup, BBQ sauce and shredded white cabbage, also costing £28.

There have been eyebrows raised over Harrods’ £28 price tag.

One said on X: “Just saw someone on TikTok buy and review a sandwich from Harrods that was £28. TWENTY. EIGHT. BRITISH. POUNDS.”

Another said: “You can buy a sandwich in Harrods for £28.”