An antibody or an antigen-binding fragment thereof with multivalent binding specificity for CD40, wherein the antibody or fragment comprises a variable light chain (V L) in which CDR1 comprises or consists of the amino acid sequence: CTGSX 1 SNIGAGYX 2 VY [SEQ ID NO:1] wherein: X 1 is S or T; and X 2 is K or H or D or G or N wherein the antibody or fragment comprises a variable light chain (V L) in which CDR2 comprises or consists of the amino acid sequence: X 3 NINRPS [SEQ ID NO:2] wherein: X 3 is G or R wherein the antibody or fragment a variable light chain (V L) in which CDR3 comprises or consists of the amino acid sequence: CAAWDX 4 X 5 X 6 X 7 GLX 8 [SEQ ID NO:3] wherein: X 4 is D or S or E or G or K; and X 5 is S or T or G; and X 6 is L or S or T or L or I; and X 7 is S or T or L; and X 8 is V or L wherein the antibody or fragment comprises a variable heavy chain (V H) in which CDR1 comprises or consists of the amino acid sequence of: GFTFSTYGMH [SEQ ID NO:28] wherein the antibody or fragment comprises a variable heavy chain (V H) in which CDR2 comprises or consists of the amino acid sequence of: GKGLEWLSYISGGSSYIFYADSVRGR [SEQ ID NO:29] wherein the antibody or fragment comprises a variable heavy chain (V H) in which CDR3 comprises or consists of the amino acid sequence of: CARILRGGSGMDL [SEQ ID NO:30] wherein the antibody or antigen-binding fragment has an affinity for CD40 of less than 1×10 -10 M wherein antibody or an antigen-binding fragment thereof are capable of binding to domain 1 of CD40 wherein the affinity for CD40 is measured by surface plasmon resonance and wherein the antibody or antigen-binding fragment thereof further comprises a cytotoxic moiety and is capable of exerting dual cytotoxic effects on CD40 + tumour cells, wherein the dual cytotoxic effects are characterised by a direct apoptotic effect on the tumour cells and an indirect immune cell-mediated cytotoxic effect on the tumour cells. wherein the antibody or fragment comprises a variable light chain (V L) in which CDR1 comprises or consists of the amino acid sequence: CTGSX 1 SNIGAGYX 2 VY [SEQ ID NO:1] wherein: X 1 is S or T; and X 2 is K or H or D or G or N X 1 is S or T; and X 2 is K or H or D or G or N wherein the antibody or fragment comprises a variable light chain (V L) in which CDR2 comprises or consists of the amino acid sequence: X 3 NINRPS [SEQ ID NO:2] wherein: X 3 is G or R wherein the antibody or fragment a variable light chain (V L) in which CDR3 comprises or consists of the amino acid sequence: CAAWDX 4 X 5 X 6 X 7 GLX 8 [SEQ ID NO:3] wherein: X 4 is D or S or E or G or K; and X 5 is S or T or G; and X 6 is L or S or T or L or I; and X 7 is S or T or L; and X 8 is V or L X 4 is D or S or E or G or K; and X 5 is S or T or G; and X 6 is L or S or T or L or I; and X 7 is S or T or L; and X 8 is V or L wherein the antibody or fragment comprises a variable heavy chain (V H) in which CDR1 comprises or consists of the amino acid sequence of: GFTFSTYGMH [SEQ ID NO:28] wherein the antibody or fragment comprises a variable heavy chain (V H) in which CDR2 comprises or consists of the amino acid sequence of: GKGLEWLSYISGGSSYIFYADSVRGR [SEQ ID NO:29] wherein the antibody or fragment comprises a variable heavy chain (V H) in which CDR3 comprises or consists of the amino acid sequence of: CARILRGGSGMDL [SEQ ID NO:30] wherein the antibody or antigen-binding fragment has an affinity for CD40 of less than 1×10 -10 M wherein antibody or an antigen-binding fragment thereof are capable of binding to domain 1 of CD40 wherein the affinity for CD40 is measured by surface plasmon resonance and wherein the antibody or antigen-binding fragment thereof further comprises a cytotoxic moiety and is capable of exerting dual cytotoxic effects on CD40 + tumour cells, wherein the dual cytotoxic effects are characterised by a direct apoptotic effect on the tumour cells and an indirect immune cell-mediated cytotoxic effect on the tumour cells.