user: Question: Which Tonnage (GRT) has a Nationality of United Kingdom, and a Name of King Gruffydd?
Columns: ['Date', 'Name', 'Nationality', 'Tonnage (GRT)', 'Fate']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['17 March 1943', 'Alderamin', 'Netherlands', 7886.0, 'Sunk']
SQL:

assistant: SELECT "Tonnage (GRT)" FROM "Table" WHERE "Nationality" = 'United Kingdom' AND "Name" = 'King Gruffydd';