Blowsy underskirts!

Who would imagine such a large and impressive moth could have such blowsy, flouncy underskirts?
This is the underside of the Clifden nonpaareli Catocala fraxini I caught in my moth trap last night.
Sometimes known as ' The Holy grail' of British moths it was much sought after in the past as it was only seen occasionally, recently however it it appears to be breeding again in the southern most counties, and this year has been exceptionally good for records. This is the second one I have had in my garden trap.
It is huge, with a wing span of nearly 10cm  and oh so flappy, and difficult to get to sit for any photos! I have added a more conventional shot in extras, showing the typical blue underwing.