A method of drilling and cleaning a wellbore during a drilling trip, the method comprising the steps of: a) providing a drill string having a drill bit at one end, and at least one cleaning tool mounted within the length of the drill string, wherein the cleaning tool comprises selectively activatable cleaning members adapted to be moved from a stowed configuration to a deployed configuration upon a body of the tool, wherein the cleaning members have magnets for use in positioning thereof; b) drilling a wellbore to a predetermined depth using the drill bit while retaining the cleaning members in the stowed configuration; c) retrieving the drill bit from the predetermined depth; d) selectively activating the cleaning members by circulating a ball in circulation fluid onto a seat at one end of an actuator sleeve in the cleaning tool to obstruct flow and cause a build up of fluid pressure; and e) ejecting the ball from the seat once the cleaning members are activated and maintaining circulation through the drill string during the cleaning operation; - characterized in that : - the cleaning members are activated by the build-up of fluid pressure within the actuator sleeve during the return trip whilst rotating the drill string to conduct a cleaning step within the wellbore using the cleaning members in the deployed configuration; and - after activation of the cleaning members and ejection of the ball from the seat the ball is captured upon a reduced internal diameter seat within and at another end of the actuator sleeve , and the actuator sleeve has outlets connected by a sleeve by-pass channel to permit fluid bypass around the ball captured upon said reduced internal diameter seat . a) providing a drill string having a drill bit at one end, and at least one cleaning tool mounted within the length of the drill string, wherein the cleaning tool comprises selectively activatable cleaning members adapted to be moved from a stowed configuration to a deployed configuration upon a body of the tool, wherein the cleaning members have magnets for use in positioning thereof; b) drilling a wellbore to a predetermined depth using the drill bit while retaining the cleaning members in the stowed configuration; c) retrieving the drill bit from the predetermined depth; d) selectively activating the cleaning members by circulating a ball in circulation fluid onto a seat at one end of an actuator sleeve in the cleaning tool to obstruct flow and cause a build up of fluid pressure; and e) ejecting the ball from the seat once the cleaning members are activated and maintaining circulation through the drill string during the cleaning operation; - characterized in that : - the cleaning members are activated by the build-up of fluid pressure within the actuator sleeve during the return trip whilst rotating the drill string to conduct a cleaning step within the wellbore using the cleaning members in the deployed configuration; and - after activation of the cleaning members and ejection of the ball from the seat the ball is captured upon a reduced internal diameter seat within and at another end of the actuator sleeve , and the actuator sleeve has outlets connected by a sleeve by-pass channel to permit fluid bypass around the ball captured upon said reduced internal diameter seat . - characterized in that : - the cleaning members are activated by the build-up of fluid pressure within the actuator sleeve during the return trip whilst rotating the drill string to conduct a cleaning step within the wellbore using the cleaning members in the deployed configuration; and - after activation of the cleaning members and ejection of the ball from the seat the ball is captured upon a reduced internal diameter seat within and at another end of the actuator sleeve , and the actuator sleeve has outlets connected by a sleeve by-pass channel to permit fluid bypass around the ball captured upon said reduced internal diameter seat . <EOS>