A multi-layer biaxially oriented film comprising a first layer (A) comprising an aromatic polyester (a) and a second layer (B) comprising a polyolefin (b) having a melting point of from 230 to 290° C. wherein said polyolefin is a styrene polymer, and an adhesive interlayer (C) between a layer (A) and a layer (B), wherein said adhesive interlayer (C) comprises a tie-layer material (c) selected from anhydride-modified ethylene copolymers in which the proportion of anhydride present in the copolymer is no more than 3.0% by weight of the polymer, and in which the ethylene copolymer comprises one or more additional comonomers other than styrene.