Ne'er cast a clout, until May is out

In other words, don't go around with your shirt off until May is out. This isn't referring to the month of May being over but rather to the flowers of the May or Hawthorn being in bloom. As they are here now. And if you have to have a man-made backdrop, Stirling Castle isn't bad. So, the sun is out and the Hawthorn is in bloom. Get those shirts off (whilst of course heeding current medical advice on safe sun exposure...)!