Does a brick attic need ventilation?
Yes, ventilation is not just for keeping the wood roof joists from dryrot, but it also keeps the attic dry so condensation does not drip on the attic insulation. Wet insulation looses its insulation qualities. 

Here in the U.S., the Building Code requires "cross ventilation" and allows less ventilation if half of the ventilation is in the top half of the attic. So, with your sloping roof, make sure there are vents in the half of the attic that is highest so the warm hot air can escape in the summer.