just saw these on screwfix and wonder if they are acceptable as they are not BS numbered...
http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=100136&ts=06454&id=39682
http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=100136&ts=06454&id=39682
http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=100136&ts=06454&id=39682
http://www.screwfix.com/app/sfd/cat/pro.jsp?cId=100136&ts=06454&id=39682