Draught horses Albert and Ivan trot down the streets of Windsor, hauling a barrel-laden cart as pubs stock up on beer ahead of Queen Elizabeth II’s Platinum Jubilee and a hoped-for influx of visitors. The two Shire breeds with black coats and feathered hooves stop to unload their cart, which later this month is set to carry Castle Hill, a beer created specially to mark the queen’s 70 years on the throne. “We call it Castle Hill because when the queen first came to the throne, the ascension was announced on the Castle Hill at Windsor,” explains Will Calvert, director of the Windsor & Eton brewe…