Structural health monitoring (SHM) usually requires several stages of information, starting from damage detection, localisation, and identification. Ultrasonic guided waves can travel long distances with relatively low attenuation, which enables them to interact with any potential damage present in the structure. This paper focuses on the use of a novel ultrasonic guided wave propagation model in order to provide both damage localisation and identification. The wave propagation model used here is a state of the art method for transient simulation of ultrasonic guided waves in one dimensional structures both isotropic and anisotropic. This is embedded in a framework for generating excitation signals and capturing scattered signals from damage at any point in the structure. The methodology computes the complete transient response at a fraction of computational cost of full finite element (FE) method. Two kind of damages are modelled: (1) a transverse crack and (2) a delamination in composite beams. To address damage identification and quantification, a model based Bayesian inverse problem is formulated so that both damage scenarios are identifiable. The proposed methodology is exemplified in a beam using the case study of a simulated delamination between two layers. The results show that the proposed framework classify and localise the damage accurately.