Wild Orchid

This wild orchid has popped up in the garden, on an area of lawn which is not cut very often. It first appeared last year. Here it is again, with two flower spikes this time. It is now marked to make sure that I don't stand on it or cut it by accident. It might be a Northern Marsh Orchid but I'm not sure. Can anyone help? Thanks to the hosts of Tiny Tuesday and Wild Fower Week.