A peptide hormone analogue which is: a compound comprising the formula X-V wherein X represents an amino acid sequence having the formula: wherein Xaa 10 is selected from the group consisting of Tyr and Leu; Xaa 12 is selected from the group consisting of Lys, His and Arg; Xaa 13 is selected from the group consisting of Tyr, Gln and His; Xaa 15 is selected from the group consisting of Asp and Glu; Xaa 16 is selected from the group consisting of Glu, Gln and Ser; Xaa 17 is selected from the group consisting of Arg, His and Lys; Xaa 18 is selected from the group consisting of Arg and Lys; Xaa 20 is selected from the group consisting of His and Gln; Xaa 21 is selected from the group consisting of Glu, His and Asp; Xaa 23 is selected from the group consisting of Ile and Val; Xaa 24 is selected from the group consisting of Gln and Glu; and Xaa 29 is selected from the group consisting of Thr and Gly; and V represents a C-terminal extension amino acid sequence having the formula Xaa i -Xaa ii -Xaa iii -Xaa iv -Xaa v -Xaa vi -Xaa vii -Xaa viii -Xaa ix -Xaa x [SEQ ID NO 291] wherein Xaa i is Gly or His; Xaa ii is absent or selected from the group consisting of Gly and His; Xaa iii is absent or selected from the group consisting of Gly and His; Xaa iv is absent or selected from the group consisting of Gly and His; Xaa v is absent or His; Xaa vi is absent or His; Xaa vii is absent or His; Xaa viii is absent or is selected from the group consisting of Ala, Glu, Gly, Gln and Ser; Xaa ix is absent or is selected from the group consisting of Ala, Glu, Gly, Gln and Ser; Xaa x is absent or is selected from the group consisting of Ala, Glu, Gly, Gln and Ser; and wherein the C-terminal residue may optionally terminate in a -CONH 2 group in place of a carboxylic acid group; and wherein V contains 4 or 5 His residues and 0, 1, 2 or 3 non-His residues; or a derivative of the compound, wherein said derivative is a derivative that has been modified by one or more processes selected from amidation, glycosylation, carbamylation, acylation, sulfation, phosphorylation, cyclization, lipidization, pegylation and fusion to another peptide or protein to form a fusion protein, and wherein said fusion protein is made by linking the carboxy-terminus of the other peptide or protein to the amino-terminus of the structure of formula; or a pharmaceutically acceptable salt of the compound or the derivative. wherein X represents an amino acid sequence having the formula: wherein Xaa 10 is selected from the group consisting of Tyr and Leu; Xaa 12 is selected from the group consisting of Lys, His and Arg; Xaa 13 is selected from the group consisting of Tyr, Gln and His; Xaa 15 is selected from the group consisting of Asp and Glu; Xaa 16 is selected from the group consisting of Glu, Gln and Ser; Xaa 17 is selected from the group consisting of Arg, His and Lys; Xaa 18 is selected from the group consisting of Arg and Lys; Xaa 20 is selected from the group consisting of His and Gln; Xaa 21 is selected from the group consisting of Glu, His and Asp; Xaa 23 is selected from the group consisting of Ile and Val; Xaa 24 is selected from the group consisting of Gln and Glu; and Xaa 29 is selected from the group consisting of Thr and Gly; and wherein Xaa 10 is selected from the group consisting of Tyr and Leu; Xaa 12 is selected from the group consisting of Lys, His and Arg; Xaa 13 is selected from the group consisting of Tyr, Gln and His; Xaa 15 is selected from the group consisting of Asp and Glu; Xaa 16 is selected from the group consisting of Glu, Gln and Ser; Xaa 17 is selected from the group consisting of Arg, His and Lys; Xaa 18 is selected from the group consisting of Arg and Lys; Xaa 20 is selected from the group consisting of His and Gln; Xaa 21 is selected from the group consisting of Glu, His and Asp; Xaa 23 is selected from the group consisting of Ile and Val; Xaa 24 is selected from the group consisting of Gln and Glu; and Xaa 29 is selected from the group consisting of Thr and Gly; and V represents a C-terminal extension amino acid sequence having the formula Xaa i -Xaa ii -Xaa iii -Xaa iv -Xaa v -Xaa vi -Xaa vii -Xaa viii -Xaa ix -Xaa x [SEQ ID NO 291] wherein Xaa i is Gly or His; Xaa ii is absent or selected from the group consisting of Gly and His; Xaa iii is absent or selected from the group consisting of Gly and His; Xaa iv is absent or selected from the group consisting of Gly and His; Xaa v is absent or His; Xaa vi is absent or His; Xaa vii is absent or His; Xaa viii is absent or is selected from the group consisting of Ala, Glu, Gly, Gln and Ser; Xaa ix is absent or is selected from the group consisting of Ala, Glu, Gly, Gln and Ser; Xaa x is absent or is selected from the group consisting of Ala, Glu, Gly, Gln and Ser; and Xaa i is Gly or His; Xaa ii is absent or selected from the group consisting of Gly and His; Xaa iii is absent or selected from the group consisting of Gly and His; Xaa iv is absent or selected from the group consisting of Gly and His; Xaa v is absent or His; Xaa vi is absent or His; Xaa vii is absent or His; Xaa viii is absent or is selected from the group consisting of Ala, Glu, Gly, Gln and Ser; Xaa ix is absent or is selected from the group consisting of Ala, Glu, Gly, Gln and Ser; Xaa x is absent or is selected from the group consisting of Ala, Glu, Gly, Gln and Ser; and wherein the C-terminal residue may optionally terminate in a -CONH 2 group in place of a carboxylic acid group; and wherein V contains 4 or 5 His residues and 0, 1, 2 or 3 non-His residues;