PMSL! Though there's absolutely nothing wrong in being duped like that - it's happened to all of us, plenty of times. I can absolutely see what went off there though. Feral Rock Doves
do demonstrate that certain flight manner, when they have somewhere to go. Fast, level, head down sort of flight. They also seem to almost be flickering their wings and keeping their backs very straight. Throw in a couple of those brown ones we see? Bingo!
Actually, if it's any consolation to ye; I have a small river a couple of hundred yards from here. One time I glanced towards it through the trees and saw a male Hen Harrier ~ or did I? Sure as hell looked like one. And I've seen a few.
Never managed to find another trace of it though. But my heightened vigilance for a while after that
did show me how many times a Wood Pigeon or a Heron might follow that damn river! I don't like to even Think which of those I thought could've been a male Hen Harrier

It happens .....