This is how you do London super-cheaply while avoiding hostels. Reservations typically cost £25 for double rooms if you book 6 months ahead, and £35 to £90 if you procrastinate. Its revelation is, to others, a curse: prefabricated room units that differ only in how little floor space you’re given (the smallest are 6 sq. m./65 sq. ft.). Beds are double-size with white duvets, with rarely an inch of space between mattress and wall. No phone, no hair dryer, no frills at all. You may find a long ledge on which to pop a travel alarm clock, but bathrooms aren’t more than plastic cubicles combining a shower, toilet, and sink in one water-splashed closet. The cheapest rooms don’t even have windows. Want to watch TV? You’ll pay £5 for 24 hours. Want housekeeping? £10. Wi-Fi is pay-as-you-use. This is no-nonsense sleep.