Interesting. The theory sounded a bit unlikely at first, albeit possible.
Then I remembered an incident in the mid 1980s, when I was fairly new to birding. I was walking up a fairly steep road near my home. On one side, the ground falls away quite sharply. There were large blocks of flats on each side, so I was looking downward between the gap (I'm not describing it too well).
I suddenly saw a falcon, quite near, cruising in level flight, in the gap between the blocks. I had no optical aid but clearly saw a dark crown, white cheeks, black moustachials. What seemed like dozens of small birds were scattering before it. What struck me was that they weren't flying away from the falcon in a controlled way but flinging themselves away in all directions, careless of where they would end up. Blind panic of a kind I haven't seen since.
At the time, I hadn't yet seen a Peregrine. Seeing my first involved driving from London to Symonds Yat in Herefordshire, where they bred. So Peregrines in London weren't on my radar. I decided that the falcon I saw, in autumn and flying in a southward direction, was probably a Hobby. Now I doubt it. It seems only a Peregrine could cause such panic.
So I guess it's quite possible these Starlings might be casualties of raptor panic.