TCR The present invention relates to an engineered T cell receptor (TCR). In particular, the present invention relates to methods for expression of a TCR when expressed as an exogenous TCR, to methods for selecting a TCR with high cell surface expression when expressed as an exogenous TCR and to methods for identifying residues which contribute to the cell surface expression level of a TCR. The present invention also relates to an engineered TCR which has a high level of cell surface expression when expressed as an exogenous TCR compared to the corresponding germline TCR sequence.