Bird with loud call

Hi!

I'm normally pretty good with garden and woodland bird songs and calls but I heard something that sounded really unfamiliar today that stopped me in my tracks.  It was in a tree in someone's garden by a busy road and was frequently calling out 2 or 3 really loud and rather shrill tweets.  From the glimpse I got it looks as though it's probably just a female blackbird but it sounds so unfamiliar to me...  Interestingly, the Merlin App didn't know it either.

I've uploaded the video to YT here as it's a 178MB file - https://www.youtube.com/watch?v=Qsr8YWq7gJo

Thanks for your thoughts!  Even if it is just a blackbird, does this call sound odd to you too?