Your hen reminds me very much of my Jemima. I don't know a whole lot about mutations...I think she's a mauve opaline sf spangle. I'll post a photo tomorrow from my OC (on an iPad at the moment).
R.I.P. Ellington (29/10/13 - 07/12/13), Iggy (07/11/13 - 11/05/14), Louis (08/01/14 - 04/05/15) and Rascal (21/08/14 - 14/04/15)