the Norse word orm, referring to their shape resembling a serpent's head. Places in Wales whose Welsh and English names appear substantially different Official policy on place-names in Wales The naming of places in Wales can be a matter of dispute and uncertainty. In some cases there is an issue of whether both the Welsh and English names should be used, or only one, and which should be given priority. In other cases it is because usage and style have changed over the years, and there is debate over which form or spelling of a placename should be used. Both the Welsh Government and the Ordnance Survey have policies on standardising place-names, drawing on advice from the Welsh Language Commissioner and the Place-name Research Centre at the University of Wales, Bangor. The policy of the Welsh Government on place-names as shown on road signs within its jurisdiction is set out in its Welsh Language Scheme. This states: "The signs for which we are responsible (mostly motorway and trunk road signs) will be bilingual. Signs which are in English only at the moment will be made bilingual when they are replaced.... When both languages are included on one sign with one language above the other, the order in which the languages appear will follow the practice adopted by the local authority where the sign is located." The latter proviso applies because local authorities have discretion over the forms used on local highway signs. In the predominantly Welsh-speaking areas of Wales, the Welsh form of the name is usually given first; in other areas, the English name is usually given first. The guidance also states: "Signs containing place names in England will contain the Welsh and English versions of the name....". This proviso has led to new motorway signs in south Wales showing the names Llundain and Bryste as well as their English-language names, London and Bristol. Welsh names for other places in Great Britain and Ireland The modern Welsh language contains names for many towns and other geographical features across Britain and Ireland. In some cases, these derive from the Brythonic names which were used during or before the Roman occupation: for example, Llundain (London), Cernyw (Cornwall), Dyfnaint (Devon), and Ebrauc/Efrog (York). The origin of the modern Welsh name for England itself, Lloegr , is disputed, but one widely believed theory – which, however, has no etymological foundation – is that