Tall purple flower

Tall purple flower

Observation - Tall purple flower. Description: This tall purple flower is growing in my garden. There is a bunch of them together growing on a dry, rocky area with little soil. I thought it was rosebay willowherb a month or two ago but now the flower has arrived it is clearly not

This tall purple flower is growing in my garden. There is a bunch of them together growing on a dry, rocky area with little soil. I thought it was rosebay willowherb a month or two ago but now the flower has arrived it is clearly not