Pat Lamb Shanks dry, and season with salt and pepper.
Heat oil in a large pressure cooker over medium-high heat. Add lamb. Cook for 6 minutes, turning, until browned all over. Transfer to a plate.
Add onion and celery to pressure cooker. Cook, stirring for 4 minutes or until starting to brown. Add garlic, rosemary and bay leaves. Cook, stirring, for 1 minute or until fragrant. Add wine. Cook for 5 minutes or until reduced by half. Add crushed tomato. Bring to a simmer.
Return lamb to pressure cooker. Secure lid. Bring cooker to high pressure. Reduce heat to stabilise pressure. Cook for 60 minutes. Release pressure according to manufacturer’s instructions. Remove lid. Stir in olives.