To help reduce the risk of women hitch-hikers being molested or raped, it might help if they were hitching, whenever possible, from beside a postbox. They would have a supply of postcards, addressed to a friend, and would write down the spot from which they are hitching and the date and time. If about to accept a lift they would complete the card by writing down the vehicle's number and then posting it - and the friend would know to raise the alarm if not receiving subsequent news of the hitch-hiker's safe arrival. The driver's knowledge that the card was posted would act as a deterrent to assault.
There could be a network of such postboxes at the main hitching points, perhaps with their installation financed by a charity such as the Suzy Lamplugh Trust (set up after the disappearance of Diana Lamplugh's daughter).
Celia Fremlin, 11 Parkhill Road, London NW3.