A child thrills to a rollercoaster ride at a theme park.A pensioner watches the rock band Queen play Bohemian Rhapsody in front of him. But all the time, they are actually on a surgeon’s table. They are wearing virtual-reality headsets that effectively distract them from surgery — using a technology that may soon mean millions of Britons can avoid having to be heavily anaesthetised, or depending on potentially addictive painkillers. Virtual reality (or VR) has been around since the 1960s when it was introduced primarily for military use to train pilots. The goggle-like device uses screens and motion sensors to create a 3D, computer-generated environment that people can interact with.It…