The downside of giving your imagination free rein is that sometimes it leads you astray. This has happened with the continuing saga of Vicky Maynard, not once but twice. At the 20,000-word mark a new character entered the narrative—a retired police officer writing an account of an unsolved murder. He visits Vicky, they discuss the case, he leaves.
Several pages later I realized that this character was blocking the development of the narrative. I deleted several thousand words and the story began to flow—until I found myself introducing a detective inspector who wants to discuss a cold case because a retired colleague had drawn her attention to inconsistencies in the evidence. The retired officer was determined to insert himself into the narrative.
The same goes for the incident of the crippled Lancaster bomber struggling to return to its base in England. It had little to do with the rest of the story so I deleted it, only to find my subconscious reviving it in a slightly different form.
Problems like this could have been avoided had I mapped out the story beforehand, and then stuck to the plan. Sadly that’s not the way my mind works.