This invention is directed to improvements in paper incorporating an elongate impermeable element, to a method of making such paper and to documents made therefrom. The invention therefore comprises a method of making single ply paper having an elongate impermeable strip at least partially embedded therein, comprising the steps of blinding one or more selected areas of a porous support surface, depositing a first layer of paper fibres onto the porous support surface around the blinded areas, bringing the strip to lie in contact with the blinded areas of the support surface such that at least edges of the strip over lie the deposited fibres, and depositing a further layer of paper fibres over the first layer and the impermeable strip to securely embed the edges of the strip within the paper, said blinded areas being impermeable to substantially prevent the deposition of fibres thereon before the security element is laid thereover and to thereby form a plurality of discrete translucent or transparent windows in a first surface of the paper in which regions of one side of the strip are exposed, wherein substantially no paper fibres are deposited along on an opposite side of the length of the strip in a region between the edges to thereby expose a continuous area of the strip at a second surface of the paper.