There is still an original box bed on view in the Tenement House museum in Glasgow. (Note that a "Tenement" was a comfortable middle class flat in a multi-unit building, with none of the connotations of poverty the word later acquired in places like New York City.) This bed was essentially built to fill a small closet, and it could be entirely hidden behind a closed door. I believe that the building dates from around 1890, and the museum part is interpreted as mid-20th-century. In fact, the rest of the building is still occupied by current residential tenants.

There's a photo of the bed on the Trip Advisor site, found here. (There's no direct link to the bed photo; you'll need to click the miniature version to see an enlargement.) The image is also near the center of the page here. In either case, look for the photo with an interior door in the center of the background.