That bike does not look like a touring frame to me; from the angle the pics are taken it looks like a racing frame or at the very least a sport frame. Most sport frames came with braze ons for panniers and fenders especially back in the day your bike was built and in Europe where and England where a lot of people tour on bikes including racing frames. If the bike was custom made, the original owner may have requested the braze ons, when I bought my first Trek, a TX900, which was a racing frame, I could have ordered it with pannier braze ons. You can club race on either of those.

531 tubing, as others have already said, was the one of the best frame tube sets ever made for a very long time, and it was very durable and had a smooth ride-depending on the geometry of the frame of course. I have a 84 531cs frame and it now has over 145,000 miles on it and still going strong with no rust anywhere.

I'am also with the crowd of people that think that steel is the real deal and it's more durable and comfortable; sure the new material is a tad lighter but if your not racing who cares? My bike when it was in it's racing form weighed 21.5 pounds; if I replaced the steel fork with a CF fork that would reduce the bikes weight by at least 1 pound, now put on some lighter wheels, CF handlebars and seat post and other odds and ends and you will begin to see a bike in the 19 pound range. Todays lighter weight 853pro tube set with Campy Record will weigh 17 pounds maybe? But that particular tubeset is very thin and easy to ding...at least according to what some folks have said on forums like this one. But wait Reynolds also made a 531pro tubeset that weighed about 1/2 pound less then mine-now your beginning to see a 18 pound bike range from a frame made back in the 80's. So I guess all my mumbo jumbo is saying that todays light weight bikes cost more money and you don't lose that much weight and you lose some durablity and comfort for what your paying.

As others have said it's all about marketing and making money.