Meanwhile German agents in England were also observing the success or failure of the V2s, and in particular where they'd landed.
However, in an effort to deceive the Germans, the British started reporting the correct time of successful attacks, while mentioning an incorrect location.
Moreover, a double agent called Eddie Chapman also fed false information back to the Germans.
As a result, the aimers never really got a grip on ranging accurately. The bombs started landing to the south east of London.
There's considerably more detail about this in Most Secret War by R V Jones, who was involved in all sorts of ruses to confuse the enemy. Well worth a read.
Eddie Chapman (Agent ZigZag) was played by Christopher Plummer in the film Triple Cross. It seems to be on YouTube.