However, after managing to get 3 kilos of plums for a ridiculously small amount in Morrisons and having made jams and chutneys seemingly endlessly, I decided that I would like to make some jelly. It came out beautifully and this is what I did - it's a bogstandard method so if you're a jelly expert, no need to read any further!
jam sugar (not preserving sugar, that is different - jam sugar has pectin added and plums are not naturally high in pectin)
Wash the plums. Remove the stones and cut off any bad bits.
Place the plums in a saucepan and add water to half way up the plums, so not an awful lot.
Bring to a simmer and cook until the plums are really soft and there is a lot of juice.
At this point, if you have a jelly bag, set it up and strain the plums through the jelly bag. I really couldn't be bothered to go out in the rain to the garage to get mine so I put a sieve over a bowl, lay a muslin inside the sieve and strain it that way. The important thing is not to squeeze or push the plums through, just let the liquid drip through. That way you get a really clear jelly. Set the pulp aside (see next entry).
Measure the liquid and for every pint of liquid add 1lb of jam sugar.
Heat slowly, stirring more or less continuously until the sugar has dissolved. Then turn up the heat and bring to a good boil.
While it is getting to a boil, put two saucers in the fridge to test for setting point and place your very clean jam jars (Not clean? Wash them then!) in a coolish oven to heat up or do what I do and boil a kettle of water and fill each jar with boiling water. While the jam is standing after reaching setting point I drain out the water and allow the heat of the jar to evaporate any remaining dampness.
After about ten minutes of boiling and stirring now and again, remove from the heat and test for setting point*. If it hasn't reached setting point, replace on the heat and boil for another five minutes or so.
When setting point is reached, remove from the heat and allow to stand for a short time. Then skim off any 'scum' (which is actually absolutely fine but spoils the look of the jelly) before ladling into the hot jars, sealing and labelling.
* I go on about setting point and saucers. This clip shows what I mean - it starts around 5:11.