try this :
http://www.ebay.com/itm/2-License-Plate-LED-kit-No-Error-Mercedes-W211-S211-E-Class-W219-CLS-R171-SLK-55-/281031498789?pt=Motors_Car_Truck_Parts_Accessories&hash=item416ec85c25&vxp=mtr&rmvSB=truebut you should be able to find them in England.