This is definitely a blackbird but it doesn't look like a male with an orange beak and glossy black feathers or a female which is brown and a bit speckled. I got my books out and after studying them I came to the conclusion that it's an immature male.
So confusing -I agree ! there is one in my garden too -- I assumed it to be a female without it speckles ! but you may be right ( he hadn't eaten all his veg to change his beak yellow !! ha ha !!)