We were over France heading to BHX as the French controller told us to hold over some VOR (which was not even directly on our routing) before crossing the channel. He didn't tell us the reason for it, however as we approached our holding he cleared us to proceed on our flight plan and handed us over to London control. The rest was as usual. We even had a on-time slot for the way back out of BHX! However, the handling agent told us that the radar in London went down!