A hydraulically damped hinge for a closure system having a closure member and a support, the hinge comprising: - a first hinge member configured to be fixed to one of: the support and the closure member, the first hinge member comprising a cylinder barrel having a longitudinal direction and extending between a first end and a second end, the cylinder barrel forming a first knuckle of the hinge and having a double-wall portion including an inner wall and an outer wall; - a second hinge member pivotably mounted on the first hinge member, the second hinge member being configured to be fixed to the other one of: the support and the closure member, the second hinge member comprising a second knuckle and a third knuckle of the hinge, the second knuckle being situated at said first end of the cylinder barrel and the third knuckle being situated at said second end of the cylinder barrel; - a torsion spring disposed within the cylinder barrel between the inner wall and the outer wall and configured for storing energy when said closure system is being opened and for restoring said energy to effect closure of said closure system, the torsion spring having a first extremity and a second extremity, the first extremity being operatively connected to the first hinge member and the second extremity being operatively connected to the second hinge member, the first extremity and the second extremity of the torsion spring are rotatable relative to one another in a first rotational direction to tension said torsion spring and in a second rotational direction opposite to said first rotational direction to unwind said torsion spring; - a dashpot disposed within the cylinder barrel and operatively coupled to the hinge members (5, 6) for damping a closing movement of the hinge; and - a rotatable tensioning element disposed in the cylinder barrel at its first end between the inner wall and the outer wall and fixed to the second knuckle, the second extremity of the torsion spring being operatively connected to the rotatable tensioning element, wherein the rotatable tensioning element is configured to allow tensioning the torsion spring during assembly of the hinge. - a first hinge member configured to be fixed to one of: the support and the closure member, the first hinge member comprising a cylinder barrel having a longitudinal direction and extending between a first end and a second end, the cylinder barrel forming a first knuckle of the hinge and having a double-wall portion including an inner wall and an outer wall; - a second hinge member pivotably mounted on the first hinge member, the second hinge member being configured to be fixed to the other one of: the support and the closure member, the second hinge member comprising a second knuckle and a third knuckle of the hinge, the second knuckle being situated at said first end of the cylinder barrel and the third knuckle being situated at said second end of the cylinder barrel; - a torsion spring disposed within the cylinder barrel between the inner wall and the outer wall and configured for storing energy when said closure system is being opened and for restoring said energy to effect closure of said closure system, the torsion spring having a first extremity and a second extremity, the first extremity being operatively connected to the first hinge member and the second extremity being operatively connected to the second hinge member, the first extremity and the second extremity of the torsion spring are rotatable relative to one another in a first rotational direction to tension said torsion spring and in a second rotational direction opposite to said first rotational direction to unwind said torsion spring; - a dashpot disposed within the cylinder barrel and operatively coupled to the hinge members (5, 6) for damping a closing movement of the hinge; and - a rotatable tensioning element disposed in the cylinder barrel at its first end between the inner wall and the outer wall and fixed to the second knuckle, the second extremity of the torsion spring being operatively connected to the rotatable tensioning element, wherein the rotatable tensioning element is configured to allow tensioning the torsion spring during assembly of the hinge.