Wuh, do you have a date? Sources suggest Jul 40 ie after Freiburg.
Found this
The attacks by the Royal Air Force (RAF) on German cities began with the attack on Wilhelmshaven on 5 September 1939.
On 11 May the British Cabinet decided to unleash the Bomber Command on the air war against the German hinterland. The following night British planes aimlessly dropped bombs for the first time on residential areas of Mönchengladbach-Rheydt. And from then on made such attacks on cities in the Ruhr area night after night. Up to 13 May 1940, i.e. two days later,the German side registered a total of 51 British air attacks on non-military targets plus 14 attacks on military targets such as bridges, railway tracks, defense and industrial plants. The first carpet bombing of a German city was in the night from 15 to 16 May 1940 in Duisburg. After that the RAF committed repeated air attacks on German cities. The night of 24th August 1940 - bombs meant to be dropped on the Thames haven oil storage depot and on the Short's factory at Rochester, by mistake or simply because they were randomly unloaded in order to escape fighters, fell on the City of London and nine other districts inside the Greater London limit. Incendiaries lit fires in Bethnal Green, and St Giles' Church in Cripplegate was damaged. Oxford Street department storeswere damaged. Nine people were killed and 58 injured.
http://fr.scribd.com/doc/87187334/Churc ... ties-FirstHis