He also wrote confidential Special Reports for the Bletchley Park Director-General, one on Second Front rumours in German signals, and another, with Peter Calvocoressi, in late 1944 on Ultra and the failure of Allied intelligence to foresee the German counter-offensive through the Ardennes in December 1944. Lucas and Calvocoressi concluded "the costly reverse might have been avoided if Ultra had been more carefully considered". For its part, Hut 3 had grown "shy of going beyond its job of amending and explaining German messages", believing that "drawing broad conclusions was for the intelligence staff at SHAEF, who had information from all sources", including aerial reconnaissance. E. J. N. Rose, head Air Adviser in Hut 3, read the paper at the time and described it in 1998 as "an extremely good report" that "showed the failure of intelligence at SHAEF and at the Air Ministry". The report is not known to have survived. It was probably the "Top Secret [intelligence] digest", a post-mortem on that failure, referred to by General Strong (1968), "both record-copies of which were destroyed". Lucas and Calvocoressi "expected heads to roll at Eisenhower's HQ, but they did no more than wobble".