user: Question: What was the date for a round that only had 1 match?
Columns: ['Round', 'Date', 'Matches', 'Clubs', 'New entries this round', 'Prize money']
Types: ['text', 'text', 'real', 'text', 'text', 'text']
Sample row: ['Extra Preliminary Round', '18 August 2007', 171.0, '729 → 558', 'none', '£500']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Matches" = 1.0;