They wore the crossed flags. In Willes book, there is a photo of signal platoon in Enlgand. As far as I recall, all wear crossed flags. I have found no reference to the removal of such badges for combat. There are photos of signals guys in Germany wearing the crossed flags on BD. There are also photos of 2nd FOU RA wearing crossed flags in Germany. However certain British members of 2nd FOU RA can be seen in photos wearing the fist and lightning bolt thingy as well.