.Like most of the home defenses they'd have been of minimal use. I suspect the politicians knew that and what they hoped for was that the enemy would be slowed down long enough for them to escape off the west coast or maybe get on the blower and say "well, actually that idea you had for us joining forces to take over the world was quite good now we've had long enough to mull it over".
Never poke fun or mock people or happenings from that era - the whole ethos and mood back then is why you can speak and write with freedom today. During the war, Doncaster Race Course had a huge hutted encampment built on it's centre and when father joined up in early '39, my mother and aunt came back to their home town and rented a flat near the course. I clearly remember her telling me of seeing a Regiment of French Colonial Troops marching past the flat, on their way from rail station to the camp only days/hours before Dunkerque - Mum always remembered how pitiful they looked. It was events like that which drove the thinking of those days. People nowadays tend to forget that experiences in the WW1 trenches influenced most of the people planning UK WW2 statistic defences - most realised that troops holding out in these fortifications would sacrifice themselves, to allow their comrades to regroup and hopefully counter attack. This type of defence was to ensure that, hopefully, the sacrifice they made was meaning full and not just a rerun of the WW1 carnage. Thankfully our fathers and grandfathers etc, were never tested in this particular way.