The present study is devoted to the quantitative characterisation of the interlayer bonding in unidirectional carbon fibre reinforced thermoplastic laminates produced by automated tape placement with in-situ consolidation (ATPisc). Two different manufacturing protocols were applied to produce the laminates that were further characterised using the quasi-static mode I double cantilever beam (DCB) test. Regardless of the manufacturing approach, the laminates exhibited multiple cracking accompanied by fibre bridging during testing, which affected the main mid-plane crack propagation. This effect was examined by comparing the crack length visually measured during testing with both the crack length back-calculated from the compliance and the crack length calculated using the flexural modulus and the compliance. In addition, the investigation of the evolution of the effective flexural modulus and the damage parameter throughout testing was performed for a better understanding of the damage accumulation in the specimens.