Rapaire, as far as I know bow hunting in the UK is illegal and has been for ages (due to the percieved likelyhood that the animal will not be immediately fatally wounded and will escape to die a long, lingering death). I believe, but could be wrong, that muzzle loaders can't be used for hunting for the same reason. The mountains should stop the bullets as long as the deer isn't on the skyline.

.22 rifles are commonly used by farmers for pest control. Deer are generally hunted in the Highlands of Scotland which have a lower population density than they did before the Highland Clearances 200 years ago.