Marsh orchid

Marsh orchid

Observation - Marsh orchid - UK and Ireland. Description: Apparently self-sown into a neglected plant pot. Unmarked leaves. Short spike of rich purple flowers. In total no more than 15cm tall. Can species be determined?

Apparently self-sown into a neglected plant pot. Unmarked leaves. Short spike of rich purple flowers. In total no more than 15cm tall. Can species be determined?