Given the task definition and input, reply with output. This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

In February 1974, the British Prime Minister, Edward Heath, advised the Queen to call a general election in the middle of her tour of the Austronesian Pacific Rim, requiring her to fly back to Britain. The election resulted in a hung parliament; Heath's Conservatives were not the largest party, but could stay in office if they formed a coalition with the Liberals. Heath only resigned when discussions on forming a coalition foundered, after which the Queen asked the Leader of the Opposition, Labour's Harold Wilson, to form a government.
When did Edward Heath ask Elizabeth to call a general election?