This is a quite interesting question for me and I have been doing a little looking on google but found just a bit.
"Long Haul Business Class
Long haul business class seats are substantially different from economy class seats and many airlines have installed "lie flat" seats into business class, whereas previously seats with such a recline were only available in international first class. There are essentially three types of long haul business class seats today. These are listed in ascending order of perceived "quality".
Herringbone seating, in which seats are positioned at an angle to the direction of travel, is used in some widebody cabins to allow direct aisle access for each seat and to allow a large number of fully flat seats to occupy a small cabin space. The concept was first developed by Virgin Atlantic Airways for its Upper Class cabin and has since been used by Delta, Cathay Pacific, Air Canada and Jet Airways, among other airlines."
And from an article in flightglobal:
"In 2003 Virgin Atlantic introduced the "Herringbone design" seat layout in it's "Upper Class" on which it had spent £50 million designing."
The article goes on to say that in fact Virgin thought they had patented the idea and were not happy when the design company started selling herringbone seats to other carriers. According to the article they apparently are suing the company and the other airlines but will probably settle out of court. Pretty ugly!
Personally I'm not sure you can really own a seat layout but I'm not a lawyer!
I'm not aware of angled seats ever being used in the golden era of aviation. However looking at an old Anet thread RFeilds made this comment
"Originally most airliner seats were rear facing because it was assumed they would be safer."
I couldn't find any info of DC-2's and stuff with sideways or rear facing seats. All the photos I could see showed them facing forwards. I think military transport aircraft have always had and still have rear facing seats (but not sideways).
There was another good page which describes all the different business layouts today, forward and angled:
So to sum up from me as far as I know it was Virgin Atlantic who first introduced the idea in 2003 with the basic herringbone. However I'd be very suprised if this is correct and someone hasn't done so before in the history of commercial aviation.
Hope it might help.
P.S. Here's another link for the design company I mentioned earlier. They claim the Virgin design was the World's first sideways facing seat. (that's what they claim anyway):
Also, have you thought of asking this question on PPrune? I'm not on there but there are lots of airline pilots and some may remember or know someone who flew in the old days.
[Edited 2012-07-06 13:22:02]