It is not that the socket covers per say are dangerous – just that there is no regulation in their manufacture and they are made all over the world. The reason for their danger is that modern UK sockets are perfectly safe but when you put in a socket cover (all designs are different and have different length pins) they often open up the shutters which activate the live socket. While they are safe when inserted – it may be a danger for small children who may play with the covers and do not insert correctly or fully causing a live socket.
While the government has not warned or made a ban on households using socket covers it has imposed a complete (UK wide) ban on the use of socket covers in all NHS premises, including doctor and dentist surgeries?
This is the first sign that the Government is taking this issue seriously!