This is a yew wood lever nutcracker dating from around the early 1800's with carved acorn decoration. There is a bevelled recess between the levers to take the nuts. Both good colour and patina.
Similar ones are illustrated In Treen for the Table page 157.
It measures 13.5cm l x 6cm w at the widest part where the carved acorn protrude., 3.5cm w in the middle.