Mild in May?

As April showers hopefully turn into May flowers, the Campaign for Real Ale is preparing to launch its annual Mild Month to promote what is still even in the ongoing revival of cask beer England's most overlooked, untrendy and maligned beer style.

I'm still not sure why CAMRA chooses May as the month to celebrate mild ale. In the first half of the twentieth century when mild was the most popular draught beer in the pub it was obviously drunk all the year round, as indeed it still is in parts of the North West and Midlands. Mild doesn't particularly strike me as a Spring beer. Does anyone in CAMRA remember why this time of year was chosen?