user: Question: Who won the Men's singles in the year that Ian Maconachie Marian Horsley won the Mixed doubles?
Columns: ['Year', "Men's singles", "Women's singles", "Men's doubles", "Women's doubles", 'Mixed doubles']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1928', 'Alan Titherley', 'R. Finch', 'J. D. M. McCallum Alan Titherley', 'Thompson-Smith Reid', 'F. L. Treasure Meredith']
SQL:

assistant: SELECT "Men's singles" FROM "Table" WHERE "Mixed doubles" = 'Ian Maconachie Marian Horsley';