I think they're some sort of campion, genus caryophyllaceae), but upside down. I'm hunting through my books now.

Look up Clarkia concinna.

I got the genus wrong, didn't I?! Onagraceae, same as the willowherbs which are so common here.

Thank you Worthy1 - Am off to have a look. I thought I knew quite a lot about plants but I seem to be sadly mistaken....!!! Thank goodness for others who know a lot more.

Hi Worthy1 - The taller plants are indeed Clarkia - thank you for that - but the single pink/red 4 petal flower still eludes me. All similar flowers of this size seem to have 5 petals.

is the red one a flax?

Yes, definitely a flax, Seaburn (only a bit late in the day!).

I've grown both as annual flowers in the summer border. I love the clarkia in particular.