What are those pretty purple wallflowers?

[Culebra]

What is the name of the tiny pretty purple wallflowers that are everywhere on people's garden walls at the moment? And can I buy seeds for them? I've got a few self-seeding on my front garden wall but I would love to speed the process along.

Someone told me they were called aubretia but when I look for aubretia seeds the flowers on the packets are pink rather than purple and the description is of a bedding plant rather than a wallflower.

Sorry I haven't mastered posting pictures yet.

campanula?

Aubretia can grow on walls. And it is purple. At least it is in my garden!

Google 'aubretia on walls' - is it those?

Thank you, yes I've now googled purple aubretia on walls and that is coming up with pictures of the flowers I meant. Campanula are pretty too though!

My google searches in the past have clearly been rubbish. I am looking for a variety name now though as my local shops that sell seeds aren't doing anything in purple.

Aha, 'purple cascade'! I have a variety name. Thanks so much, you've got me on the right track now! I'll order some seeds online.