An interesting an uplifting anecdote of true impulsiveness found in John Julius Norwich's 1990 Christmas Cracker. Viscount Norwich was a jotter before jotting was invented - an Ur jotter. Respect. His Cracker booklets are sent to a few thousand of his closest friends and consist of information and wisdom culled from his library and also presumably sent to him by loyal correspondents.
Vincenzo Valdrati or Valdré (1742-1814) was an Italian painter-architect who came to England in the 1770s and designed, inter alia, several of the state rooms at Stowe before settling in Ireland where he became Architect to the Board of Works. From Howard Colvin's superb Biographical Dictionary of British Architects I learn that "while at Stowe he attended a wedding and when the bridegroom failed to appear, he was so moved at the bride’s distress that he chivalrously offered himself as a substitute – and was accepted."