“Work Hard. Have Fun. Make History.” So reads a sign above the entrance to Amazon’s newest UK “fulfilment centre” (or warehouse) in Hemel Hempstead.

Inside lies more than 40,000 sq m of shelving, packing lines and millions of products. One area where larger products are stored is known as “pallet land” and adjacent, at another end of the space sits “the tower”, where several floors of shelving are stacked on top of each other. Pickers constantly, and more or less silently, walk up and down the tower’s lengthy aisles, pushing carts into which they deposit items purchased by someone, somewhere online.

Founded at the dawn of the web in 1994, Amazon is now reportedly worth $247bn (£157bn). But the company is not, in fact, hugely profitable. What keeps Amazon afloat? As for any business with tight margins, efficiency is key.