A twin shaft pump comprising two cooperating rotors (10, 12) configured to rotate in opposite directions about parallel axes of rotation (30, 32); a stator comprising a stator bore in which said rotors (10, 12) are mounted to rotate; said stator bore comprising a central part between said two axes of rotation (30, 32), and an outer part outside of said two axes (30, 32), said rotors (10, 12) being configured to have cooperating dimensions with said stator bore such that an outer edge of each rotor (10, 12) that is remote from the other rotor seals with said stator bore when rotating in at least a portion of said outer part; a fluid inlet in said stator bore, at least a portion of said fluid inlet being in said central part of said stator bore between said axes of rotation (30, 32); a fluid outlet in an opposing surface of said stator bore, said fluid outlet being in said central part of said stator bore; said fluid inlet and fluid outlet being arranged such that on rotation of said rotors (10, 12), said rotors (10, 12) each move a pumping chamber between said fluid inlet and said fluid outlet; wherein at least a portion of said fluid inlet is arranged to extend beyond said central part of said stator bore; and characterised in that said fluid outlet and fluid inlet are arranged such that an opposing outer surface of each of said rotors (10, 12) moves beyond an edge of said fluid outlet prior to said outer surface of said rotor (10, 12) sealing with said stator bore beyond said fluid inlet, such that said pumping chambers between said stator bore and each of said rotors (10, 12) is in fluid communication with both said fluid inlet and said outlet for a fraction of each rotor rotation. two cooperating rotors (10, 12) configured to rotate in opposite directions about parallel axes of rotation (30, 32); a stator comprising a stator bore in which said rotors (10, 12) are mounted to rotate; said stator bore comprising a central part between said two axes of rotation (30, 32), and an outer part outside of said two axes (30, 32), said rotors (10, 12) being configured to have cooperating dimensions with said stator bore such that an outer edge of each rotor (10, 12) that is remote from the other rotor seals with said stator bore when rotating in at least a portion of said outer part; a fluid inlet in said stator bore, at least a portion of said fluid inlet being in said central part of said stator bore between said axes of rotation (30, 32); a fluid outlet in an opposing surface of said stator bore, said fluid outlet being in said central part of said stator bore; said fluid inlet and fluid outlet being arranged such that on rotation of said rotors (10, 12), said rotors (10, 12) each move a pumping chamber between said fluid inlet and said fluid outlet; wherein at least a portion of said fluid inlet is arranged to extend beyond said central part of said stator bore; and characterised in that said fluid outlet and fluid inlet are arranged such that an opposing outer surface of each of said rotors (10, 12) moves beyond an edge of said fluid outlet prior to said outer surface of said rotor (10, 12) sealing with said stator bore beyond said fluid inlet, such that said pumping chambers between said stator bore and each of said rotors (10, 12) is in fluid communication with both said fluid inlet and said outlet for a fraction of each rotor rotation.