Identification help - Hartlepool Headland

Hi all, I'm very new to birding and really beginning to enjoy it.

I spent a very blowy morning at Hartlepool Headland. My knowledge is developing, and I was able to see Cormorants, Turnstones, Oyster Catchers, plenty of gulls and even a Bar-Tailed Godwit. However, I saw a bird I have since spent the morning trying to identify to no avail. I was stood at the top of a rocky beach, with a number of bushes and shrublands in front of me. The following bird was near the edge of the shrubland.

Size - Blackbird-size

Body colour - Pale creamy/yellow-ish colour.

Tailfeathers -black and white

Beak - medium-sized,; quite sharp.

Legs - dark-coloured

Unfortunately, didn't have my camera out as I was heading home when I saw it. Any help greatly appreciated!