An electrosurgical instrument for applying radiofrequency energy and/or microwave frequency energy to biological tissue, the instrument comprising: a distal part comprising an instrument tip for applying radiofrequency energy and/or microwave frequency energy to biological tissue, wherein the instrument tip comprises a first conductive element and a second conductive element; a coaxial feed cable comprising an inner conductor, a tubular outer conductor coaxial with the inner conductor, and a dielectric material separating the inner and outer conductors, the coaxial feed cable being for conveying radiofrequency energy and/or microwave frequency energy to the distal part; wherein: the inner conductor is electrically connected to the first conductive element and the outer conductor is electrically connected to the second conductive element through a rotatable connection between the distal part and the coaxial feed cable that allows rotation of the distal part relative to the coaxial feed cable about a central axis of the distal part; the instrument comprises an actuator for rotating the distal part in a first rotational direction relative to the coaxial feed cable; the instrument comprises a tubular housing in which the coaxial feed cable is received; the distal part is rotatably mounted at a distal end of the tubular housing; characterized in that: the instrument comprises a biasing element configured to rotationally bias the distal part in an opposite second rotational direction when the distal part is rotated in the first rotational direction; and the biasing element is connected to the distal part and to the tubular housing. a distal part comprising an instrument tip for applying radiofrequency energy and/or microwave frequency energy to biological tissue, wherein the instrument tip comprises a first conductive element and a second conductive element; a coaxial feed cable comprising an inner conductor, a tubular outer conductor coaxial with the inner conductor, and a dielectric material separating the inner and outer conductors, the coaxial feed cable being for conveying radiofrequency energy and/or microwave frequency energy to the distal part; wherein: the inner conductor is electrically connected to the first conductive element and the outer conductor is electrically connected to the second conductive element through a rotatable connection between the distal part and the coaxial feed cable that allows rotation of the distal part relative to the coaxial feed cable about a central axis of the distal part; the instrument comprises an actuator for rotating the distal part in a first rotational direction relative to the coaxial feed cable; the instrument comprises a tubular housing in which the coaxial feed cable is received; the distal part is rotatably mounted at a distal end of the tubular housing; characterized in that: the instrument comprises a biasing element configured to rotationally bias the distal part in an opposite second rotational direction when the distal part is rotated in the first rotational direction; and the biasing element is connected to the distal part and to the tubular housing. the inner conductor is electrically connected to the first conductive element and the outer conductor is electrically connected to the second conductive element through a rotatable connection between the distal part and the coaxial feed cable that allows rotation of the distal part relative to the coaxial feed cable about a central axis of the distal part; the instrument comprises an actuator for rotating the distal part in a first rotational direction relative to the coaxial feed cable; the instrument comprises a tubular housing in which the coaxial feed cable is received; the distal part is rotatably mounted at a distal end of the tubular housing; characterized in that: the instrument comprises a biasing element configured to rotationally bias the distal part in an opposite second rotational direction when the distal part is rotated in the first rotational direction; and the biasing element is connected to the distal part and to the tubular housing. the instrument comprises a biasing element configured to rotationally bias the distal part in an opposite second rotational direction when the distal part is rotated in the first rotational direction; and the biasing element is connected to the distal part and to the tubular housing.