A vacuum cleaning head comprising: a housing having a suction opening for admitting an air flow to the head; an agitator for agitating a surface to be cleaned, the agitator having an active state and an inactive state; a duct for receiving the air flow from the housing; and: a control assembly for controlling the state of the agitator, the control assembly comprising: a pressure chamber having an interior volume in fluid communication with the duct and which is variable between an expanded configuration and a contracted configuration in response to a pressure difference between the interior volume and ambient air; an actuator for changing the state of the agitator in response to a transition of the pressure chamber to the contracted configuration; characterized by a control mechanism (214, 238) having a first state for preventing the pressure chamber from adopting the contracted configuration, and a second state for allowing the pressure chamber to adopt the contracted configuration, the control mechanism (214, 238) being arranged to change between the first and second states in response to an increase in the interior volume of the pressure chamber. a housing having a suction opening for admitting an air flow to the head; an agitator for agitating a surface to be cleaned, the agitator having an active state and an inactive state; a duct for receiving the air flow from the housing; and: a control assembly for controlling the state of the agitator, the control assembly comprising: a pressure chamber having an interior volume in fluid communication with the duct and which is variable between an expanded configuration and a contracted configuration in response to a pressure difference between the interior volume and ambient air; an actuator for changing the state of the agitator in response to a transition of the pressure chamber to the contracted configuration; characterized by a control mechanism (214, 238) having a first state for preventing the pressure chamber from adopting the contracted configuration, and a second state for allowing the pressure chamber to adopt the contracted configuration, the control mechanism (214, 238) being arranged to change between the first and second states in response to an increase in the interior volume of the pressure chamber. a control assembly for controlling the state of the agitator, the control assembly comprising: a pressure chamber having an interior volume in fluid communication with the duct and which is variable between an expanded configuration and a contracted configuration in response to a pressure difference between the interior volume and ambient air; an actuator for changing the state of the agitator in response to a transition of the pressure chamber to the contracted configuration; characterized by a control mechanism (214, 238) having a first state for preventing the pressure chamber from adopting the contracted configuration, and a second state for allowing the pressure chamber to adopt the contracted configuration, the control mechanism (214, 238) being arranged to change between the first and second states in response to an increase in the interior volume of the pressure chamber. a pressure chamber having an interior volume in fluid communication with the duct and which is variable between an expanded configuration and a contracted configuration in response to a pressure difference between the interior volume and ambient air; an actuator for changing the state of the agitator in response to a transition of the pressure chamber to the contracted configuration; characterized by a control mechanism (214, 238) having a first state for preventing the pressure chamber from adopting the contracted configuration, and a second state for allowing the pressure chamber to adopt the contracted configuration, the control mechanism (214, 238) being arranged to change between the first and second states in response to an increase in the interior volume of the pressure chamber.