The little daisy you see dotted around the stonework in the formal gardens is Erigeron karvinskianus.
Once you get it to settle in it will easily self seed all over your garden. if flowers from early summer through to the first frosts. If left it can get a bit leggy and woody so every autumn (after it has started going to seed) it gets a big hair cut.
Not only does the big chop help the growth of the plant for next year but from a practical point of view it helps us to tidy up as all the autumn leaves get tangled up in them.