Omitted to mention, Jas, that the protection consists of hauling its dead-weight bulk into the garage in freezing spells as it's kept in a twenty inch tub.
It's now too big to get in through the greenhouse door so the unheated garage has to do. It has occasionally dipped below freezing in there and soft new growth has been damaged before now. As Winter finishes it often gets a fungal attack which consists of red spotting on the older leaves. These are removed in Spring when new leaves are on the move.
It's stayed in the same pot for the last seven years as I've no intention of trying to lift it with a crane into a larger container. It gets fed weekly with Phostrogen or Miraclegrow in Summer and sends out the odd ariel root from the base of the trunk into the compost.
Otherwise it seems to thrive on neglect.