What is the bird I can hear in my garden?

CAN anybody help me identify a bird that is making an unusual noise in my garden in northern Newbury?

It is a single high-pitched note that is about the G above middle C.

I haven't been aware of it in the past but have spent more time in the garden during lockdown and I keep hearing it. I listened to different bird song on the internet but didn't find it.

KATE OPPEL

Dene Way

Newbury