This is Lychnis chalcedonica ‘Dusky Salmon’, a lovely early long flowering perennial with strong upright stems and gorgeous pinky salmon cross shaped flowers hence it’s common name of Maltese Cross or Jerusalem Cross.
It produces masses of seed and I decided to sow some fresh in early October to see if it would germinate. As you can see, it did, all of it!
How wonderful nature is! It never ceases to amaze me!