Pick over the fruit, discarding anything mouldy or bruised. Rinse well and put into a pan with the wine, spices and bay leaves.
Set on a gentle heat until the juices run. Bring to the simmer and cook gently for 5 minutes, until the grapes start to collapse.
Use a potato masher to crush the grapes and liberate the pips. Simmer for 10 minutes more or until the grapes are completely soft.
Line a large sieve with a muslin or linen tea-towel and set over a calibrated jug or bowl. Pour in the contents of the pan and let the liquid strain through undisturbed for an hour or so, or overnight. This process should yield 600ml juice.
If you don't have a sugar or jam thermometer, put a couple of saucers in the freezer now to check setting point in due course.
Next, sterilise a selection of jars either (a) by running through the dishwasher at a high temperature (b) by filling half-full with cold water and microwaving for 3m or (c) by washing in soapy water and rinsing well. In all cases, dry the jars upside down in an oven set at 140?C for at least 30 minutes. Any other paraphernalia - measuring jug, tongs, jam funnel, ladle etc - should also go into the oven to be sterilised, and while the oven is on, warm the sugar in a stainless steel bowl for about 20m - not absolutely necessary but it does make the sugar dissolve faster when added to the juice. Keep the jars in the oven until ready to pot. They will be less likely to crack on impact with the hot jam, and they will keep sterile up to the last moment.
Line up waxed discs, cellophane pot covers, discs and labels, and prepare a tray, lined with kitchen towels for the jars to sit on while they cool.
Pour the strained juice into a clean pan and add the sugar and lemon juice. Set on a high heat, bring to the boil and bubble until it registers a solid 105°C on a jam thermometer. Once it is on the button, remove from the heat. Alternatively, after 10 minutes, drop a teaspoon of juice on your frozen saucers. Wait for a minute then run a clean finger through it to see if it's gelatinous and wrinkly. If it runs back together immediately, boil for another 5 minutes and test again with the other saucer. If it still hasn't set, pot it anyway and hope for the best. Slightly runny jelly is better than grape-flavoured concrete.
When setting point is reached, don some asbestos hands, remove the jars from the oven with the tongs and prepare to pot, using a jam funnel or small glass jug. Fill each jar to the brim while the jelly and the jars are still hot, and top with a waxed disc, shiny side in contact with the jelly. Cover with a round of cellophane, moistened and stretched across the mouth of the jar and secured with a rubber band. Allow to cool before securing the lid. Label artistically.
Officially, I have to say that this keeps for several months unopened but between you and me, I am currently enjoying the 2011 vintage, matured to spicy perfection in the attic. Best not try that at home though unless you are willing to face the consequences.