Why are valuation rolls for Lanark County (with few exceptions) available only in Edinburgh?

One copy of each valuation roll produced by the Lanark County Assessor was sent to Edinburgh to be kept for historical and legal research at Register House (now the National Records of Scotland). Another copy was kept by the Assessor’s office in Lanarkshire. When the Scottish counties and burghs were abolished in 1975, the surviving valuation rolls (and voters’ rolls) Scotland’s city, district and regional archive services attempted to preserve the valuation rolls and voters rolls for their areas. In most cases they were successful. In the case of Lanark County, the valuation rolls and voters’ rolls belonging to Lanark County Council were removed or destroyed, either by staff in the outgoing County Assessor’s office or by local officials in the successor authority, Strathclyde Regional Council, before staff from the newly created Strathclyde Regional Archives could secure them for preservation. Among the Lanark County records held by Glasgow City Archives there is a valuation roll for Lanark County for 1894, and among the records of several civil parishes with the Lanark County records there are series or individual rolls for those parishes. The National Records of Scotland hold valuation rolls for Lanark County from 1855 until 1975.