Oral Answers to Questions — British Army. – in the House of Commons on 7th May 1940.
asked the Secretary of State for War at what hour the news first reached the War Office of the German invasion of Denmark; and at what hour the information was communicated to the Chief of the Imperial General Staff?
News that German troops had crossed the Danish frontier was received between 2 a.m. and 3 a.m. on 9th April. The information was conveyed to the Chief of the Imperial General Staff at about 3.30 a.m.