Please ID this gorgeous plant as I want to get more

[Vibbytu]

Last year I bought lots of random plants to fill my new garden giving little consideration to height etc. This year this wonderful plant has sprung up. Curently about 4ft tall and has been flowering for weeks. It's probably in the wrong place but is stunning and I want to get more. Can anyone advise what it is please.

Looks like wild phlox. It's also known as Dames Rocket, Mother of the evening, Sweet Rocket or Summer Lilac.

Thanks SparklyGlitterballs

So it will self seed and is invasive?

Hesperis matronalis - sweet rocket. Biennial or short lived perennial. You could sow seeds now for next year.

Could it be erysimum bowles mauve?

No, flowers look similar but leaves are different.