OK: I've compiled the answers so far (mainly from Baz!) for the first 10.
How exact does the name have to be, i.e. do we need to name the specific species of lily?
I think #1 and #7 are technically French Marigolds and Queen Protea respectively, but apart from that, the only one I can add is #8. That's an American plant: Ammannia Robusta, known as the Grand Redstem - don't know if it has a common British name?
1) French Marigold
2) ?
3) ?
4) Lavender
5) Hibiscus
6) Lily
7) Protea
8) Grand Redstem
9) Foxglove
10) Hollyhock