A valved container assembly comprising: a container for containing a fluid, the container extending in an axial direction and having an open front end; a valve (14; 14') disposed in the container, the valved container assembly being configured so that forward axial movement of the valve relative to the container is inhibited; and a plunger element disposed axially rearward of the valve, the plunger element being axially moveable in the container and defining a first volume in the container between the plunger element and the valve, where the plunger element is configured to increase the pressure of a fluid in the first volume upon forward axial movement relative to the valve; characterised in that the valve comprises: a permanent seal fluidly sealing the valve to the interior of the container about the entire perimeter of the valve; and a channel bypassing the permanent seal, the channel having a first opening in fluid communication with the atmosphere outside of the valved container assembly and a second opening selectively sealed from the first volume by a resilient seal (22; 22'); wherein the resilient seal is moveable between a sealing configuration and an open configuration to selectively seal the channel from the first volume, wherein in the sealing configuration the resilient seal fluidly seals the valve to the container so as to fluidly isolate said second opening of the channel from the first volume, and in the open configuration the second opening of the channel is in fluid communication with the first volume; and wherein the resilient seal is moveable from the sealing configuration to the open configuration upon fluid pressure in the first volume exceeding a first pressure threshold. a container for containing a fluid, the container extending in an axial direction and having an open front end; a valve (14; 14') disposed in the container, the valved container assembly being configured so that forward axial movement of the valve relative to the container is inhibited; and a plunger element disposed axially rearward of the valve, the plunger element being axially moveable in the container and defining a first volume in the container between the plunger element and the valve, where the plunger element is configured to increase the pressure of a fluid in the first volume upon forward axial movement relative to the valve; characterised in that the valve comprises: a permanent seal fluidly sealing the valve to the interior of the container about the entire perimeter of the valve; and a channel bypassing the permanent seal, the channel having a first opening in fluid communication with the atmosphere outside of the valved container assembly and a second opening selectively sealed from the first volume by a resilient seal (22; 22'); wherein the resilient seal is moveable between a sealing configuration and an open configuration to selectively seal the channel from the first volume, wherein in the sealing configuration the resilient seal fluidly seals the valve to the container so as to fluidly isolate said second opening of the channel from the first volume, and in the open configuration the second opening of the channel is in fluid communication with the first volume; and wherein the resilient seal is moveable from the sealing configuration to the open configuration upon fluid pressure in the first volume exceeding a first pressure threshold. a permanent seal fluidly sealing the valve to the interior of the container about the entire perimeter of the valve; and a channel bypassing the permanent seal, the channel having a first opening in fluid communication with the atmosphere outside of the valved container assembly and a second opening selectively sealed from the first volume by a resilient seal (22; 22'); wherein the resilient seal is moveable between a sealing configuration and an open configuration to selectively seal the channel from the first volume, wherein in the sealing configuration the resilient seal fluidly seals the valve to the container so as to fluidly isolate said second opening of the channel from the first volume, and in the open configuration the second opening of the channel is in fluid communication with the first volume; and wherein the resilient seal is moveable from the sealing configuration to the open configuration upon fluid pressure in the first volume exceeding a first pressure threshold.