Its already been confirmed by the eyewitness in question that he mistook Nevill's body for a woman.
I am afraid that the eyewitness account you seek to rely on is unreliable because PC Collins and PC Delgado looked in through the laundry room window, they having approached the targeted entry door on white side, after leaving their original position at the corner of white red, and using the curved wall for cover. The six man raid team all went passed the kitchen window and therefore could not possibly have mistook Neville Bambers body, simply because once the six man raid team went beyond that kitchen window, four of them stayed at the entry door whilst Collins and Delgado went beyond that door to the next window, which was the laundry room window, but which was often also referred to amongst the family as the back kitchen window. The body which Collins and Delgado both saw when they peered into the laundry room via it's window, was the body of a woman, which could not have been Neville Bambers body because his body was concealed in front of an internal door of the main kitchen - just to be perfectly clear about this, neither PC Collins, or PC Delgado would have been able to see into the main kitchen when they peered into the laundry room via the laundry room window, because the main kitchen was on the other side of an internal door which was not only closed at the time they looked in through the laundry room window, but once the raid team managed to get into the farmhouse by smashing the farmhouse door in, they found that there was something very heavy behind that internal door which prevented them from entering the main kitchen quickly! You are too keen to buy into the claim made by the cops to try and get rid of the female body from being present at all anywhere downstairs, whether it be in the laundry room, on the floor behind the door, or in the main kitchen, and even later still, on the far side of the bed, laid on top of the bed, before Sheila's body ended up dead on the main bedroom floor! The claim by Collins that once he got into the kitchen he realised that he had mistook Neville's body for the body of a woman doesn't hold water, it's riddled with inconsistencies. For a start nobody looking in through the main kitchen window would have been able to see Neville's body at all anywhere, because he was sat there on one chair, with the upper part of his body and arms being supported by a second chair placed in front of him - this arrangement was pushed into the corner of the kitchen, right up against the opening edge of the internal kitchen door spoken about earlier! The angle was too acute for any body standing outside the kitchen window peering into the kitchen, and because the angle was too acute, Collins and Delgado couldn't have made the mistake they claim they made, and in any event they looked in through the laundry room window which was a completely different room to the main kitchen. For example the laundry room was through the window on the left of the entry door, and the main kitchen was through the window on the right of the same door. Additionally, the timed police radio log contents then come into play, and it becomes clear that the sort of mix up which Collins and Delgado want us all to buy into couldn't have happened because there was always mention of the body of one dead male, or a man, on each of the consecutive occasions after which there was mention of a dead female body, or woman...
For 10 solid minutes there were messages being passed back and forth, and in all of them reference to there being two bodies found upon entry to the kitchen, the body of one dead male, and the body of one dead female, one dead male, one dead female, a man, a woman, a murder, and a suicide - and on top of all this, only a further three bodies found upstairs, two bodies downstairs, three bodies upstairs, five dead in total, as accurately recorded by the contemporaneously recorded and timed police radio log contents..
The witness statement version of the alleged events were made up much later on, when the cops knew what they had to cover up!