Hue:
"As for the distance, the home station had very good antennas and receivers, trained operators, and higher powered transmitters."

Until some years ago, Geoff Linthorne, Vk2GL - now SK - was a member at our local radio club - Westlakes Radio Club.  Geoff was British and had actually been to Bletchley Park.  He was old enough to remember when British soldiers marched through this village after being dumped on English beaches from Dunkirk.  His family billeted a Belgian officer.  As the group marched past Geoff's house (ie his mother's house) the platoon sergeant assessed the size of the house and shouted 'One in there'. 

After the war Geoff trained with British Telecom (or whatever is the official name).  At one time he was at Bletchley, where he loaded Enigma coding machines onto trucks to be carted away and buried.  Geoff told me he greatly regretted not stealing one or two; alas he was under strict instruction about how to handle these 'things' and he followed instructions to the letter.

My regret is not having a tape recorder when Geoff was around.  His experience in the RAF (where he trained as a radio operator & top turret gunner) gave him an appreciation of fact and decency that is rare today.  Now to your point of 'good aerials' and 'powerful transmitters'.

According to Geoff, there was an aerial "farm" some km from Bletchley.  He made the point that it was sufficiently distant that no spy or photographer would link the aerial farm and Bletchley.  You can understand I wish I had recorded  some of Geoff's memories. 

All the bes to yout, Hue

Leslie