Thank you. Must have been a spectacular sight, I was at work so missed it but I've been shown videos of large numbers over home as well. Even a rough estimate of 300 is more useful than a range for bird records :)
I saw at least 100 over Wanniassa just after midday today. Many were as low as the tree tops, some were dots high in the sky. I didn't have my camera with me, unfortunately. It has been almost 13 years since I've seen this species of bird in Canberra, but well worth the wait. Thrilling sighting! Well done with the photos.