Popular works of fiction claim that after breaking the Enigma in Bletchley, some sophisticated mathematics or statistical techniques were used to hide this fact of breaking (not necessarily by the same people). This may have included at looking at probabilities of certain war time events, and probabilities of their chance intervention, to estimate whether some acquired information could be acted upon and by whom. Popular history writing is filled with anecdotes of sending spy-submarines regularly to "spot" the already known locations or sending letters to fake spies for blame.
Are the stories of sophisticated or even simple data analysis or model building for this purpose at some level of british intelligence for these reasons a myth? Or are some historical details known on this (these kind of historical materials are assumedly very difficult to preserve due to their sensitive nature)? It has been given a surprisingly specific form in popular fiction writings.