 This is a multi-centre, non-randomised, open label Phase I clinical trial of an Advanced Therapy Investigational Medicinal Product named CD19 Chimeric Antigen Receptor CAR γδT-cells CD19 CAR γδT-cells in patients with high risk, relapsed CD19 haematological malignancies Leukemia and lymphoma. Following informed consent and registration to the trial, Patients will receive the allogeneic CD19 CAR γδT-cells following lymphodepleting chemotherapy. The study will evaluate the safety, efficacy and duration of response of the CD19 CAR γδT-cells in patients with high risk relapsed CD19 malignancies. 