A T cell which expresses a gamma-delta T cell receptor and a chimeric antigen receptor, wherein the TCR is used to provide a signal 1 for γδ T cell activation and the CAR is used to provide a costimulatory signal 2 wherein the CAR comprises: (i) an antigen binding domain; (ii) a transmembrane domain; and (iii) a co-stimulatory intracellular signalling domain from a T cell signalling co-receptor which on binding of antigen to the antigen binding domain of the CAR provides a co-stimulatory signal and transmits signal 2 to the gamma delta T cell and does not transmit signal 1 to the gamma delta T cell upon binding of the target antigen; the gamma delta TCR and the CAR arranged such that the gamma delta TCR provides signal 1 and the CAR provides signal 2 upon binding to each receptor respectively wherein the gamma delta T cell will only be fully activated and capable of killing a target cells which expresses a first antigen capable of binding to the gamma delta TCR and a second antigen which is capable of binding to the CAR; and wherein the intracellular signalling domain comprises a DAP10 signalling domain; wherein the antigen binding domain is capable of binding to GD2 or CD33; wherein the transmembrane domain comprises a CD8 stalk or a CD28 transmembrane domain; wherein the CAR further comprises a spacer domain between the antigen binding domain and the transmembrane domain; and wherein the spacer domain is defined by an Fc region. (i) an antigen binding domain; (ii) a transmembrane domain; and (iii) a co-stimulatory intracellular signalling domain from a T cell signalling co-receptor which on binding of antigen to the antigen binding domain of the CAR provides a co-stimulatory signal and transmits signal 2 to the gamma delta T cell and does not transmit signal 1 to the gamma delta T cell upon binding of the target antigen; the gamma delta TCR and the CAR arranged such that the gamma delta TCR provides signal 1 and the CAR provides signal 2 upon binding to each receptor respectively wherein the gamma delta T cell will only be fully activated and capable of killing a target cells which expresses a first antigen capable of binding to the gamma delta TCR and a second antigen which is capable of binding to the CAR; and wherein the intracellular signalling domain comprises a DAP10 signalling domain; wherein the antigen binding domain is capable of binding to GD2 or CD33; wherein the transmembrane domain comprises a CD8 stalk or a CD28 transmembrane domain; wherein the CAR further comprises a spacer domain between the antigen binding domain and the transmembrane domain; and wherein the spacer domain is defined by an Fc region. the gamma delta TCR and the CAR arranged such that the gamma delta TCR provides signal 1 and the CAR provides signal 2 upon binding to each receptor respectively wherein the gamma delta T cell will only be fully activated and capable of killing a target cells which expresses a first antigen capable of binding to the gamma delta TCR and a second antigen which is capable of binding to the CAR; and wherein the intracellular signalling domain comprises a DAP10 signalling domain; wherein the antigen binding domain is capable of binding to GD2 or CD33; wherein the transmembrane domain comprises a CD8 stalk or a CD28 transmembrane domain; wherein the CAR further comprises a spacer domain between the antigen binding domain and the transmembrane domain; and wherein the spacer domain is defined by an Fc region.