I am fairly certain Talflows were rarely factory fitted. They were shipped to India to retrofit bikes.
The 80 India Office Norton 16H machines made and delivered in 1946 did however have the Talboys aircleaners fitted by Norton.
The ones found last years were were likely removed when the bikes were sold-off/discarded and forgotten for many years.
So too the M20's and C11's supplied to the India Office. I had thought that the batch that was found (all in red oxide primer) Were surplus and never fitted? Maybe someone else can confirm. Ron