Unknown bird with a large vocabulary

Hi all!

I need your help with identifying a bird call. Hopefully you can hear it in the video attached, I was awoken this morning by this vocal friend who seems to have quite a large vocabulary! They repeat a phrase or call 3-4 times before switching to a different phrase and repeating it and so on. The sounds are at times mimicing - there's a telephone-like trill in there and alarm-like noises as well as some kissy sounds. I've spent a few hours searching and listening to multiple different birdsongs online to try and figure out the likely suspect but haven't come across anything quite like this. Initially I thought blackbird but I'm not sure it's a match.

I live in south London and heard the same call in our local park last week in the evening. I didn't manage to capture any footage of it then but thankfully have had another chance. The video was too large to upload here so I've popped it on YouTube so you can hear it too.

https://youtu.be/3iYKGtlW-5M

Would love to hear your thoughts!