1. Cook the new potatoes in boiling salted water until just tender, then drain. Cool slightly, and then remove the peel.
2. Cut potatoes into thick slices.
3. Cook the French beans in boiling salted water until tender. Drain and cool, then cut into halves.
4. Cook the spaghetti in boiling salted water following the pack instructions. Drain in a colander.
5. Return spaghetti to the pan, add the potatoes and beans. Reheat gently together.
6. Add the pesto and toss all the ingredients together. Season to taste.