It is Leaves from the Luminosity range by Red Rooster, and is probably 3-4 years old. I've almost used all of mine, and would love a little or a lot - I'd happily buy 5 metres of it! You can see more of the range here. It's the lilac I really want, but I'd also like to get my hands on some of the pink, and there was also a navy blue I'd like more of.
UPDATE - Found, thank you!