The size of the leaves looks more like Leucanthemum vulgare, Ox Eye Daisy. Those tallest stems will flower soon. Looking at the picture I'm guessing you're in the UK. In which case this is native and pretty but can spread about by seed. Easily pulled up though.

The cultivar comes out strongly colored and then becomes less purple as the season advances. It does not leaf out green and then turn purple later. Some purple leaved tree cultivars do yield a percentage of purple seedlings but since tree cultivars are typically considered to be clonal (unlike named seed strains of flowering annuals and annual vegetables) a purple seedling of a 'Forest Pansy' would still not be an example of that same named variety. An exception is certain Rose Family trees such as mountain ashes and hawthorns that may give off apomictic seedlings, that is ones resulting from a particular asexual seed production process on the tree. Such seedlings are clones of the parent specimen. But when seeds are gathered from these trees and seedlings raised from them it is not known under ordinary circumstances if apomixis was involved until the plants raised get big enough to show they are true to type.

A few years ago (2016) I planted some allium bulbs. They were allium Giganteum, allium Gladiator, allium Purple sensation, alllium Mount Everest and allium sphaerocephalon. I planted them in October. The next year all of them flowered except for a. sphaerocephalon. I thought it needed some time to establish. I let them go to seed. This year, only a few Purple sensation flowered, no signs of any white Mount Everest, no signs of Giganteum nor Gladiator. Sphaerocephalon hasn't flowered yet. I fear they are lost. Could it be they are dormant this year? Did they die off? I also bought a. moly, a. caeruleum and a. oreophilum last year and planted them in late fall (December) as the soil was workable and no freezing temperatures. This spring only a few of them flowered although I planted 10 of each. As with my alliums I always leave leaves on, never tear them off. I live in a city so no special animals. No voles nor mice. There are a lot of slugs, though. I have a sandy loam, neutral soil. Climate is something between oceanic and Mediterranean with hot (sometimes dry sometimes humid) summers and dry winters with the lowest temp. - 12 degrees C (around 11 F). (I won't post any photos because this is the third time I am posting this so something is apparently glitched.) Thanks for replies in advance

Yeah, I can cut that back with little effect on the plant. unlike the poor plants you saw at the store. There are several painted strands of leaves on mine. It doesn't seem to be bothering the plant at all, so I'll just wait until the spring prune. I'm more careful when painting now! I used to do my spray painting in the garage, but my husband has the crazy idea that we should keep the car in there!