I was recently shown a copy of your ENIGMA, a radio friend let me have it and I really enjoyed it as I never expected to see a "numbers" publication in the U.K. I am particularly keen on the "Lincolnshire Poacher" as I was in the Lincolnshire Regiment and that was our regimental march. Just before his unfortunate death in April 1993 "The Laughing Cavalier" told me that he had a contact in RAF Communications. This source had told him that "LP" originated in Cyprus and the jammers originated in Iraq. The RAF, Army and Government had numerous facilities on the island for making such transmissions. At first the Laughing Cavalier thought they came from the UK because 7887 was a BBC feeder  from Daventry. The Iraqis had few jammers left after the war and sometimes had to put their clandestine jammers onto the counter intelligence front. They often had two different sounding jammers obliterating two different frequencies because they were short of a particular type. The 3/2 step English stations are CIA and not NSA and transmit from Germany and Virginia. Some are jammed by Iraq and some by CIS ( Jamming sounds similar because jammers are Russian supplied). The CIA was taking advantage of Russia's problems to step up their HUMINT activities against them and to gather intelligence on what was happening there as they were concerned about the safety of their strategic nuclear weapons and needed political intelligence on the state of the Russian government. He confirmed to me that many jammers originated in Russia. He also said the Czech Drums and Trumpet station originated in VRATISLAWICE and the Rumanian Skylark station originated in BRANESTI in Rumania.
He told me that his RAF contact had done DFing for him and that "LC" had details of the locations various transmitters. He died of a heart attack at his home in London and I have been unable find details of his "numbers" listening (he had done it since 1961). Virtually all German broadcasts originate in Germany and those in USB are BND broadcasts from various transmitters all over Germany. He originally thought that "LP" came from Hanslope Park but after hours of sitting at the perimeter fence with a receiver he decided that it did not. He said that broadcasts ending in 00000 were Russian and the English man replaced that woman with the phoney British accent who also ended in zeroes.