I've wondered for decades why an airline hasn't done this - so easy and cheap to do; so rewarding and sensible for the horrid world of flying which used to be great for us Concorde users (I was the Most Concorded flyer with almost 400 flights over the life of the plane from the very first to nearly the last).
www.dailymail.co.uk/travel/travel_news/a...returning-class.html