The roof is nearing completion now. For a "belts and braces" approach, we've installed vents at eaves and ridge level, to ensure a good through-flow of air above the insulation envelope and thus reduce the risk of condensation/timber decay.
At the front of the gable there was originally a ridge finial - still to be seen on neighbouring properties. Some Googling lead me to this website, where believe it or not this guy specialises in making reproduction finials - amazing what you can find online! This one is a close match to the one our house would have originally had...