A method of deploying a fibre optic assembly for a communication network where the fibre optic carries data or for sensing a property associated with a structure of interest where the fibre optic is a sensor, the assembly comprising: an elongate member formed from a laminate of at least two layers constructed and arranged so as to be configurable between a coiled form and an extended form, wherein when coiled the member is wound about an axis extending transversely to the longitudinal extent of the member, and wherein when extended the member has a form in which it has a curved cross-sectional profile, the member being resiliently biased in that form; and, at least one fibre optic disposed along at least a part of the longitudinal extent of the member, the method comprising: uncoiling the elongate member and positioning the fibre optic assembly, wherein at least a part of the fibre optic is fixed to the member such that in uncoiling the member the bending stiffness of the member automatically achieves a desired tension in said part of the fibre optic; and then, burying the fibre optic assembly, wherein the elongate member in its extended form provides a stiff and resilient substrate in itself, and without the fibre optic assembly being clipped around a supporting structure or the structure of interest when positioned prior to being buried, wherein the substrate maintains the position and tension of that part of the fibre optic from loads experienced by the fibre optic assembly that would act to deform the position and tension of that part of the fibre optic whilst the fibre optic assembly is being buried, wherein if the fibre optic is for a communication network, the fibre optic is buried in the ground (151,152) and wherein, if the fibre optic is a sensor, burying the fibre optic assembly comprises forming the structure of interest around the fibre optic assembly or introducing a filler material to form an infilling in the space between the fibre optic assembly and the structure of interest such that the fibre optic assembly is coupled to the structure by the infilling and changes in the property of the structure are transmitted to the fibre optic assembly such that it can be sensed by the sensor. an elongate member formed from a laminate of at least two layers constructed and arranged so as to be configurable between a coiled form and an extended form, wherein when coiled the member is wound about an axis extending transversely to the longitudinal extent of the member, and wherein when extended the member has a form in which it has a curved cross-sectional profile, the member being resiliently biased in that form; and, at least one fibre optic disposed along at least a part of the longitudinal extent of the member, the method comprising: uncoiling the elongate member and positioning the fibre optic assembly, wherein at least a part of the fibre optic is fixed to the member such that in uncoiling the member the bending stiffness of the member automatically achieves a desired tension in said part of the fibre optic; and then, burying the fibre optic assembly, wherein the elongate member in its extended form provides a stiff and resilient substrate in itself, and without the fibre optic assembly being clipped around a supporting structure or the structure of interest when positioned prior to being buried, wherein the substrate maintains the position and tension of that part of the fibre optic from loads experienced by the fibre optic assembly that would act to deform the position and tension of that part of the fibre optic whilst the fibre optic assembly is being buried, wherein if the fibre optic is for a communication network, the fibre optic is buried in the ground (151,152) and wherein, if the fibre optic is a sensor, burying the fibre optic assembly comprises forming the structure of interest around the fibre optic assembly or introducing a filler material to form an infilling in the space between the fibre optic assembly and the structure of interest such that the fibre optic assembly is coupled to the structure by the infilling and changes in the property of the structure are transmitted to the fibre optic assembly such that it can be sensed by the sensor. uncoiling the elongate member and positioning the fibre optic assembly, wherein at least a part of the fibre optic is fixed to the member such that in uncoiling the member the bending stiffness of the member automatically achieves a desired tension in said part of the fibre optic; and then, burying the fibre optic assembly, wherein the elongate member in its extended form provides a stiff and resilient substrate in itself, and without the fibre optic assembly being clipped around a supporting structure or the structure of interest when positioned prior to being buried, wherein the substrate maintains the position and tension of that part of the fibre optic from loads experienced by the fibre optic assembly that would act to deform the position and tension of that part of the fibre optic whilst the fibre optic assembly is being buried, wherein if the fibre optic is for a communication network, the fibre optic is buried in the ground (151,152) and wherein, if the fibre optic is a sensor, burying the fibre optic assembly comprises forming the structure of interest around the fibre optic assembly or introducing a filler material to form an infilling in the space between the fibre optic assembly and the structure of interest such that the fibre optic assembly is coupled to the structure by the infilling and changes in the property of the structure are transmitted to the fibre optic assembly such that it can be sensed by the sensor.