Roll up, roll up, the greatest show on earth has just begun: the British and Irish spring is under way again. High on my list of unforgettable spring experiences is always the March afternoon on which you meet the first musical willow tree of the year. I never fail to be taken by surprise when all at once, after a whole winter of silence, the common species of goat and grey willow hum with bees. The welcome insects have come to feast on the flowering catkins, and they throng the trees in huge numbers.