the use of the tool 10 in a tubing expansion operation will be described with reference to fig4 to 9 of the drawings the tool 10 comprises a mandrel 14 having a connector 16 at one end to allow the tool 10 to be releasably mounted at the lower end of a tool string as will be described the connector 16 incorporates an internal fishing profile to allow retrieval of the tool 10 following a tubing expansion operation mounted to the lower or leading end of the mandrel 14 is a compliant expansion cone 18 the cone 18 is compliant in the sense that the cone 18 is sized to induce a slight diametric expansion of the tubing 12 but if the cone 18 should encounter an immovable restriction the slots 20 in the cone 18 permit a degree of radial deflection such that the cone 18 is not stuck fast on encountering such a restriction the function of the cone 18 is to treat and clean the inner surface of the tubing 12 as the tool 10 advances through tubing 12 as will be described and also to ensure that the tubing 12 is of a consistent cylindrical form that is the cone 18 will tend to remove any ovality or dents in the tubing wall the cone 18 thus conditions the tubing 12 to facilitate operation of a seal member in the form of a swab cup 22 which is mounted on the mandrel 14 directly behind the cone 18 as will be.