This is my Mother-in-law Elsie’s recipe for Yorkshire Parkin. Elsie died in 1990 aged 82 and going through an old cookery book of hers recently, I came across this recipe in her own handwriting.
Method.
Melt the margarine and golden syrup. I usually put these in bowl and microwave for about 40 seconds until a runny liquid.
I used golden syrup when making this but black treacle can also be used or a mixture of golden syrup and treacle would be good.
I used plain flour and sifted this with the ginger and bicarbonate of soda into the bowl, added the sugar and oatmeal and a beaten egg and approximately quarter of a pint of milk. I used a rounded teaspoon of both the ginger and the bicarb (as much above the spoon as in the spoon)
Mix firmly until a soft dropping consistency is formed.
Pour into a lined tin. Mine is 11ins by 7ins. Perhaps a 9inch square tin would be similar.
Bake in a preheated oven. 150 degrees/ fan 140degrees for approx 1 hour or until the cake begins to leave the edges of the tin.
Check after 50mins on the cooking progress.
Parkin whilst can be eaten straight away seems to be better for keeping and becomes moist and sticky after keeping in an airtight container for 3 or 4 days…. If you can wait that long!!
Enjoy!!
Please be aware that in the United Kingdom:
Oatmeal is ground grains of oats like coarsely ground flour and can be used to make cookies, biscuits etc.
Porridge oats are rolled (flattened) oats, can also be used in baking but usually used for porridge or muesli.
‘Treacle’ in this case is probably the name given to Golden Syrup and is not always ‘Black Treacle’
eviesgran 
I see you used golden syrup. You really should try it with the black treacle, as the flavour is much improved by it. Black treacle or molasses were what was traditionally used for proper Yorkshire Parkin, Mum made it every bonfire night.
I’ve tried a few parkin recipes, all great as I’m sure your recipe is using black treacle. I found this recipe amongst my Mother in law’s recipe books and I must say it is delicious. I tried this recipe for sentimental reasons, as she has now been dead for 22 years and would have been 104 yrs old now.