What’s a home without a den? Whether it’s for lounging in a nook, having a cosy Sunday breakfast or simply giving the kids a good space to play, the addition rarely goes unappreciated. And they’re not just for twee little cottages - in the era of open-plan living and minimalist decor, we are more than ever in need of retreats to escape the stresses of daily life. Here are 20 dens for the modern household.