Melt the butter in a medium saucepan and cook the onion gently over a low heat for five minutes until soft. Add the pears and raisins and cook for ten minutes.
Add the mixed spice, vinegars, sugar, cranberries, orange zest and juice and port, stir well and cook for another ten minutes or so.
Season with a little salt and pepper. Taste and then add more sugar or vinegar to your own taste – it may need some more, or you may be bang on! This is best served warm.
If you are not using the chutney straight away, transfer it to a lidded plastic container and store in the fridge for up to ten days. Heat through gently before serving.