Primrose Jam sounds familiar but I'm not sure why, when I get a moment this weekend I'll look in my old cookery books and seeI've made and have an old recipe for Primrose Wine and also Primrose Vinegar.
4 Quarts Primrose Petals
1 Gallon Boiling Water
1 Tbsp Culinary Orange Flower Water
3 1/2lb Granulated Sugar
1 Tsp General purpose yeast
Put the flowers into a clean sterlised bucket (ideally with a lid or cover with a thick towel or cling film), add the boiling water, slice the fruit and add at this stage also, loosely cover the bucket with the lid leave to stand for 5 days stir the wine and squeeze the fruit everyday.
After 5 days add the sugar and stir until dissolved, and strain into a demijohn, add the orange flower water and yeast amd leave to ferment out.
Primrose Vinegar (Taken from Hilda Leyel's 'The Gentle Art of Cookery')
Boil six pounds of castor sugar in four gallons of water for 10 minutes, and take off the scum. Shake into it a peck (16 dry pints) of primroses, and wehn cool spread some yeast on a piece of toast and put in the liquid. Let it ferment all night, then put it in a barrel and keep it in a warm place till it has done working. There must be an air hole in the top of the barrel. In several weels the vinegar can be bottled for use.
Alternatively you can fill a year with primrose flowers and top up with cider vinegar to make a quick floral vinegar. Whist I was trying to find some info online about Primrose jam I came across a recipe on the UK Food website for Parsnip and Primrose Pie http://uktv.co.uk/food/recipe/aid/517065 which sounds bizarre but may be worth a try?
Maybe you could try using a rose petal jam recipe and substitute primorse flowers? If I do come across a recipe I'll post it here, good luck and do let us know what the finished primrose goodies turn out like