In 1911, in the Scottish Border village of Sprouston, the young parish minister wrote to the Daily Mail for entry forms for its sweet pea competition.The top prize was a staggering 1000 and organisers predicted that as many as 15,000 would enter. He could not foretell that the paper's estimate of the number of competitors would be more than doubled, or that a fortnight before the deadline a nation-wide drought would threaten the very existence of...