Overwintering bees has always beeen a worry to beekeepers. The single brood box system is not really suitable, discounting this hopefully one off freak winter, especially where the spring weather has been cold, wet and windy as in recent years. I overcame the weakness of the single by using a 'canopy of sugar bags, 6 - 8 thoroughly dampend sugar bag, placed in early September, right on the frame tops in way of the cluster. The bags were usually reduced to paper tatters by late October and were replaced by another 4 - 6 dampened bags. The colonies are checked around Xmas and more bags with the paper merely wetted donated where necessary. This system worked well until 2010! My opinion about optimum overwintering is - follow Ian Craig's system of double brood box management, with the top box stowed out with stores. Next man down would be the brood and super, this super also chock full of stores. The most important prerequisite for succesful overwintering, all things being equal is a young queen - by a young queen I mean ideally a current year queen entering her first winter. In the presence of Varroa many queen bees carry the mite all summer, where the beekeeper has been less than diligent with anti Varroa measures, such queens will have been debilitated by parasitisation and by the start of the second winter - not really fit for purpose! A colony requeened around early July will boom in good foraging conditions - or where fed if the weather denies the bees acces to the late nectar sources. Bees returning from a good heather season with such a queen will be bursting with bees - it is the beekeepers job to keep them healthy and well fed from early September. It is quite astonishing just how much brood a colony denied access to the late nectar flows can produce on the late autumn feed - and thererby hangs the threat - the beekeeper feeds what is deemed adequate in the autumn; hefts the hive in ate October - finds it satisfyingly heavy - but the weight could be made up of a large complement of young bees and an inadequate amount of stores for overwintering. The bees having used the bulk of th efed syrup to breed! This was the situation which encouraged my use of sugar bags in the first place! If winter 2010 turns out to be the norm - it might be well to think about straw boxes around the hive - similar to the WBC double walled hive, provided due care was taken with ventilation.