More now on the confusion over face coverings in england. Borisjohnson has indicated that england is likely to follow scotland by making face coverings mandatory in shops. He said the government would be looking at tools of enforcement in the coming days and an announcement would be made shortly. In a moment we can speak to dr sander van der linden who is a specialist in social psychology at the university of cambridge, but first lets speak to dr margaret harris, a spokeswoman for the world health organization. Thank you for your time. What is the who advice to government in the uk as to what it should do . Good evening. The important thing with face coverings for the general public, it has the charming term, the chatterjee is source control. We are trying to limit the amount of virus that is potentially around, especially in enclosed indoor settings. If everyone thought of themselves as infectious, that would work. If we all thought of ourselves as infectious, we would do all the things, keep their hands clean, keep the mouth covered and essentially limit transmission. Is not one of the problems that the who and many governments have not said if it is creative these masks are necessary and the public has taken that message on board and is ambivalent about winning then . Initially we we re about winning then . Initially we were certainly focusing on masks for Health Workers as they were in the highest risk setting. If you remember at the beginning when the outbreaks were accelerating in europe, there were no supplies of face masks so there was concern that the face masks would be snapped up and hoarded. Now, especially as people have learned to make their own where we all can wear them so we are certainly encouraging people to wear them, especially when they cannot socially distance and when they are at in an indoor