Metro tiles are as ubiquitous as flat white coffee. In fact, the two often go hand in hand. They have become the go-to splashback wall-covering for the perplexing number of coffee shops that keep popping up in all our urban centres. Dublin is a caffeine addict’s paradise these days, with no sign of the coffee-shop spread slowing. Metro tiles are in upmarket restaurants too – and in homes, of course. Go to a tile showroom or the tile section in your local DIY superstore and you’ll encounter a huge variety of metro tiles. They’ve become the most popular choice for shower-rooms, en suites and kitchen splashbacks because they’re smart, modern and relatively inexpensive.

By rights they should be called subway tiles (as they are in the US) because the classic 3-inch by 6-inch white glazed tile first came into use in 1904, when designers George C Heins and Christopher Grant L Farge created them for the new New York subway. They added all sorts of Beaux Arts-inspired embellishments around them – colourful bas reliefs, detail-heavy pictorial plaques and ceramic signs to indicate clearly to travellers, who might not all speak English, which stop was which. The decorative aspect of their design isn’t much copied now but the plain subway tiles are, particularly laid out in a “brickwork” design although Heins and Farge also used herringbone and other options.

And that’s the point of them: they are practical. They were originally chosen by the germ-fearing Victorians because they could be so easily cleaned and the colour white allows for light reflection down in the depths of the subway. Now metro tiles come in different sizes – not for purists, who still go for the 3-inch by 6-inch version – and there are bevelled options and a huge range of colours and finishes.