On the first night of the barrage, which was the heaviest, they are said to have fired 500,000 shells, i.e. at an average cost of £5 per shell, £2½ millions worth. But well worth it, for the effect on morale.
 When the Germans first bombed London, there appeared to be no anti-aircraft defence. Sometimes a single plane could be cruising above and people could only wait anxiously, often for seemingly long periods, for a bomb to be dropped. At other times there would be a concentrated attack of incendiary bombs, high explosives, or both. After all the anti-aircraft guns available had been regrouped around London, quite unexpectedly they all opened up on the night of 10 September. Orwell is absolutely correct about the effect on morale. See also 12.9.40. Peter Davison