The sun is out, the skies are clear and today is International Picnic Day, the perfect excuse to swap your desk for a picnic blanket and spend the afternoon lounging in one of London’s lovely green spaces. Party and events experts, The Brighton Bucket List, explain how to get the most out of this fun day. A Quick Look at the Origins International Picnic Day, celebrated every 18 June, may not be the most formal date on the calendar, but it is definitely one of the most fun. The idea of a picnic goes back centuries, with the word pique-nique…