On July 15, 1996, in a shabby little room at Court Number One, Somerset House, it took all of three minutes to dissolve the marriage of the century. H.R.H. the Prince of Wales and H.R.H. the Princess of Wales, neither of whom was present, were listed as Couple No. 31. Somerset House is less than a mile from St. Paul's Cathedral, where, on another July day, a dashing prince had waited at the altar for the shyly smiling 20-year-old bride in the billowing ivory taffeta wedding dress.