A method of manufacturing a tubular component comprising the steps of: (a) rough machining the exterior surface of a solid billet of material to reduce the size thereof and form at least a first radially extending flange and a second radially extending flange on the exterior of the billet, said flanges (3, 5) being centred on and axially spaced along the longitudinal axis of the billet; (b) machining a bore which extending axially in the billet; (c) performing a first probing operation on the interior surface of the bore in order to check the concentricity of the interior surface about a flange axis which extends longitudinally between the centres of the first and second flanges (3, 5) by measuring any variation in the distance of the internal surface from the said flange axis around the inner circumference of the bore at a first point within said first flange, a second point within said second flange, and at least a third point which is longitudinally spaced between said first and second flanges (3, 5); (d) performing a first straightening operation on the billet in order to reverse any curvature along the longitudinal axis outside of allowed tolerance for the component identified in the billet by measurement of variations in the distance of the inner surface of the bore from the flange axis around the inner circumference of the bore at any of the measurement points during the first probing step which are outside of allowance tolerance for the component; (e) performing a further machining operation on the outside surface of the billet to reduce the wall thickness of the bore; (f) measuring the wall thickness of the bore around the circumference of the billet at least at two different axial positions along the billet in order to confirm uniform wall thickness around and along the billet within allowable tolerance for the component; (g) checking the billet to identify any remaining curvature about the longitudinal axis of the bore; (h) performing a further straightening operation on the billet to correct any curvature outside of allowable tolerance detected in step (g); (i) performing a final machining operation in order to form any ports and upstands which are required in the component and to remove any other unwanted material from the exterior of the billet; and (j) performing a fine honing operation on the longitudinal bore in order to reduce the wall thickness and the diameter of the bore to the final specified values. (a) rough machining the exterior surface of a solid billet of material to reduce the size thereof and form at least a first radially extending flange and a second radially extending flange on the exterior of the billet, said flanges (3, 5) being centred on and axially spaced along the longitudinal axis of the billet; (b) machining a bore which extending axially in the billet; (c) performing a first probing operation on the interior surface of the bore in order to check the concentricity of the interior surface about a flange axis which extends longitudinally between the centres of the first and second flanges (3, 5) by measuring any variation in the distance of the internal surface from the said flange axis around the inner circumference of the bore at a first point within said first flange, a second point within said second flange, and at least a third point which is longitudinally spaced between said first and second flanges (3, 5); (d) performing a first straightening operation on the billet in order to reverse any curvature along the longitudinal axis outside of allowed tolerance for the component identified in the billet by measurement of variations in the distance of the inner surface of the bore from the flange axis around the inner circumference of the bore at any of the measurement points during the first probing step which are outside of allowance tolerance for the component; (e) performing a further machining operation on the outside surface of the billet to reduce the wall thickness of the bore; (f) measuring the wall thickness of the bore around the circumference of the billet at least at two different axial positions along the billet in order to confirm uniform wall thickness around and along the billet within allowable tolerance for the component; (g) checking the billet to identify any remaining curvature about the longitudinal axis of the bore; (h) performing a further straightening operation on the billet to correct any curvature outside of allowable tolerance detected in step (g); (i) performing a final machining operation in order to form any ports and upstands which are required in the component and to remove any other unwanted material from the exterior of the billet; and (j) performing a fine honing operation on the longitudinal bore in order to reduce the wall thickness and the diameter of the bore to the final specified values.