Slice the lemon, put into a pan with the red wine, sugar and cinnamon stick and bring to a boil. Simmer gently for about 10 minutes.
Peel the pears, but leave the stalks on. Take the cinnamon stick and lemon slices out of the red wine and stand the pears upright in a deep pan.
Pour the wine over the pears (they should be covered in wine), put a lid on the pan and poach over a low heat for about 10 minutes.
Take the pears out of the poaching liquid and stand on individual plates. Boil the red wine until reduced to a syrupy consistency,
Halve the walnuts and mix into the sauce. Pour the hot red wine sauce over the pears.