Most people in Colonsay will normally drive at between 25mph and 40mph and all will be wearing a seatbelt; and most people do slow down considerably when passing pedestrians (who should have stepped off the road and be standing still whilst the vehicle passes).  It is well worthwhile to slow down like that, just in case the pedestrian stumbles.  Even at a low speed, accidents happen – in the 1880s a local man in his mid 50s was killed when struck by a cart whilst walking on the roadside at Achadh Tarsuinn.  The official figures suggest that one should slow to 20mph or less when passing a pedestrian standing clear of the road.
RoSPA says: The most recent analysis of the role of vehicle speed in pedestrian fatalities in Great Britain found that 85% of pedestrians killed when struck by cars died in collisions that occurred at impact speeds below 40mph, 45% at less than 30 mph and 5% at speeds below 20 mph.
The risk of a pedestrian who is hit by a car being killed increases slowly until impact speeds of around 30 mph. Above this speed, the risk increases rapidly, so that a pedestrian who is hit by a car travelling at between 30 mph and 40 mph is between 3.5 and 5.5 times more likely to be killed than if hit by a car travelling at below 30 mph. However, about half of pedestrian fatalities occur at impact speeds of 30 mph or below. Elderly pedestrians have a much greater risk of suffering fatal injuries than other age groups.