Last summer, M&S shoppers couldn’t get enough of the Strawberry & Creme Sandwich. The limited-edition launch became a social media sensation, with more than one million sandwiches sold in just five weeks.

Now, M&S is back with another headline-grabbing creation: the Chocolate, Strawberry & Pistachio Sandwich.

But the most interesting story isn’t what’s inside the sandwich. It’s how it was made.

Behind the launch sits a major manufacturing investment from long-term supplier partner Greencore, which has opened a dedicated new nut production facility at its Northampton “fortress factory” — one of the specialist sites focused entirely on producing M&S products.

The purpose-built facility, known as the “nut room”, has been created to safely handle nuts at scale, unlocking new possibilities for M&S’s food-on-the-move range.

For product developers, that’s a game changer.

The new facility allows M&S to bring together ingredients, flavours and textures in ways that were previously more difficult to manufacture consistently across millions of products. It also creates opportunities for future innovation, opening the door to a new generation of sandwiches, wraps, salads and snacks featuring nut-based ingredients.

The Chocolate, Strawberry & Pistachio Sandwich is the first product to emerge from this investment — combining sweet strawberries, rich chocolate and crunchy pistachios in a flavour combination designed to surprise and delight customers.

It’s a reminder that viral products don’t happen by accident.

Behind every trending launch is a network of product developers, manufacturing specialists and supplier partners working together to turn bold ideas into reality.

For M&S and Greencore, the new nut facility is more than just a factory upgrade. It’s an investment in innovation, ensuring the business can continue creating the products that customers love — and that social media can’t stop talking about.