What does this sentence mean. I'm translating a text about the Lucy spy ring and I can't understand one sentence. Here’s the extract: "In October 1939 the British Embassy at Bern was informed that Hitler proposed to launch an attack against Belgium, Holland, and north-eastern France on November 12.Whether this information was accepted by the British as being reliable is not known, but it was in fact true. Hitler’s chance postponement of the attack could have led the British to distrust any other information from this source, which stemmed from the very heart of the Wehrmacht itself, the OKW." I don't understand the last sentence. At first I thought it was subjunctive, but since Hitler did postpone an attack on France, I decided that I was wrong. Does this sentence mean that because of Hitler's postponement the British stopped trusting this information source? And I also don't understand what is "chance postponement".