I believe it was an FT story. Reuters ran similar stories in October 2012 and April 2013 without the 29 trillion number.
I think you are correct, it was FT. But it is important no matter the source. It changes my investment strategy.
Smart people know the system is doomed to crash. The question is when. The Ponzi could go on for a long time, in which case betting against the house is not an option.