Battle of Britain won date

[Shikhov]

Thank you Sirs!
It seems to me according to Graham Boak' info Oct.31 1940 became BoB Victory date in March 1941. But I've read that October 25, 1940 British Government was informed about one Ultra interception re one vital Luftwaffe Transport Command disbanded that means Invasion halted. War Cabinet and Churchill as Cabinet Chairman discuss matter October 31 and concluded that Invasion at least in 1940 not happen. Soon Army rediness declined. But Churchill was advised about mentioned Ultra interception in Sept.17 evening and soon photoreconing admit the fact. But information for public still closed in September and October. And seems later ?!
In my opinion Government could be affraid another "victory" like Sept.15 when London was bombed during whole day after or if Victory claimed.
In September population losses increased in 8 times and still the same level in October. May be this is reason instead Invasion possibilities and airsuperiority ?