(Thirteen extras were hired to be in the pictures found in the darkroom. We'll assume that that includes the Harvest Festival photographs...)
Counting backwards from the pics we do see, I’d say the first pic on the wall that the missing pic is on is from 1965. Then 1966, 1967 and 1968, two at a time. There are also 4 pics in the nook immediately past these. (The Ingrid Pitt script says they go back 20 years. Also that the girls are 13 years old.)
1965 - Girl has her hands by her side.
1966 - Girl is holding her hands in front of her. Her dress is shorter than the girl in the 1965 pic. This could be the same background as the 1970 pic but the girls are different.
1967 - Girl is thinner than the one in the 1968 pic.
1968 - Girl is wider than the one in the 1967 pic.
1969 - No date on it. This is the first harvest festival photograph we see close-up. Since we then see pics from 1970, 1971 and then the spot where the 1972 pic should have been, it is safe to assume that this picture is from the 1969 festival. Girl has medium length hair. Hands at her side. Round veg/apples under spray of wheat on the top row on the left. What looks like two stacked cow pie-shaped leaves of bread in front of her left foot. Several long dark, probably vegetables but could be bread on the far right of the top row.
1970 - The girl is holding her hands in front of her.
1971 - Girl has braids. It looks like 3 watermelons on top row on right, 3 loaves of long bread on bottom, This is the same background as the pic described below that hangs in the bar of the Ellangown Hotel but a different girl is in each pic.
1972 - Rowan (Geraldine Cowper's face "photoshopped" onto Lesley Mackie's body.)
The original pic with Lesley Mackie's face. Geraldine Cowper (who played Rowan) wasn't available to pose for her harvest festival photograph so Lesley stood in for her.
The pics for the years 1969 - 72 and the pic of an unknown year from the Ellangowan Hotel are all different girls. It’s too hard to tell how many of the others are different.
Some have the exact same layout for the background: 1966 (probably), 1970, 1971 and the pic from the Ellangowan Hotel for example. 1967 and 1968 could have the same backgrounds too.
There appear to be 2 pictures on each wall of nook B (see floorplans)… (Probably reprints of the known 4. None ever get zoomed in enough to see.) Let's call them pic A, B, C and D with A and C being the furthest away and B and D being the ones closet to us.
pic A - Girl is short
pic B - Can't see this one
pic C - A short girl
pic D - A tall girl.
A & C are not the same.
There is also a pic, taken by John Brown as I would assume, all of these were, that hangs in the Ellangowan Hotel bar in a newspaper article. No year is shown. It shows a girl with her hands at her side. Her hair is blond and cut in a bowl shape. She is wearing white high socks. There is no apple crate on the right. There are three large loaves of bread next to a sun-faced bread loaf in the center bottom. There is a crate of apples to the left. There is an unknown object to our right of her feet. It looks like 3 watermelons further over to the right on the top row.
This is the same background but a different girl as the 1971 pic. It’s too hard to tell but it doesn’t appear to be one of the ones by the nook either. The text below it reads:
"This "Summer Isle" annual harvest festival photograph hung in the bar of the hotel featured in the cult film, The Wicker Man filmed in Galloway. The owner of the Ellangowan Hotel in Creetown where the scene was shot was given the photograph as a souvenir and it has been presented to the museum on extended loan.""Photographer John Brown with acknowledgements" is written below."
(Photo by Jamie Stuart. 3/4/10, Yahoo group. The musuem would be the Creetown Heritage Museum.)
Here is a reminiscence of one girl who was picked out to have her picture taken for one of the harvest festival photographs. She says her pic didn't make it into the movie but it could be that it just wasn't focused on. This document is on display at the Creetown Heritage Museum.Catherine McEwan and Wendy McLaughlan, possibly, were also models for these pics. All were students at Douglas Ewart High School in Newton Stewart.
See also this pic used in the film treatment for The Wicker Man II, written by Shaffer.