|On the rooftop of the garden shed at Paul's house: John, Paul, George and Mike!|
Here's the story: The back of 20 Forthlin Road overlooked the grounds of the Police Training College, headquarters of the Liverpool Mounted Police.
Paul and his brother would watch them training horses, knocking pegs out of the ground with lances just as they had done in the British Raj. "We used to sit on the concrete shed in the back yard and watch the Police Show every year for free," Paul remembered. "One year, Jackie Collins came to open it and we were entranced at the sight of her comely young figure." (Barry Miles / Paul McCartney, Many Years From Now).
Peter Hodgson in true Columbo style has come up trumps here. The film was made in 1958 (not 1950 as it says on YouTube). take a look at the film, but the interesting part is around the 34.33 mark.
What you're looking at here is the 1958 Police show with the rear of Forthlin Road across the back of the field. The McCartney's home, no.20 was/is the third house to the left from the three storey flats seen on the right. What's very exciting about all this, seen more clearly on my screenshot, is that Peter has noticed several figures sitting on the roof of the outside toilet of no.20 watching the show. Today, Paul McCartney's brother Mike had a look at the footage and confirmed to a Liverpool reporter that the figures are John, Paul, George and Mike himself.
More at the There Are Places I Remember blog