The benefits of leaf seals with respect to providing sealing in gas turbine engines is well known but wide scale applicability is hindered by the costs and manpower necessary for assembly of leaf seals. By utilising a concertina fold of a band or strip 50, 80 in which leaf seal elements 51, 52 are defined with leaves seal sections 52, 82 and spacers 53, 83 defined at tilt angles appropriate for the eventual lay angle in a leaf seal assembly more automated manufacture of leaf seal assemblies is achieved. The means by which the leaf seal sections 51, 81 are formed ensures that the spacers 53, 83 have a thickness greater than the leaf seal element 82a and generally side portions are provided with folding sections 56, 86 which are sacrificially removed during forming of leaf tufts 140 for final assembly within leaf seal assembly 1.