I have always found that it as notoriously hard to get a good set when making Strawberry jam. I now use the following method and you are guaranteed to have a well set jam.
1 KG Strawberry’s
1KG Sugar.
4 lemons.
1Pint water
Cut each lemons into 8 pieces, put into pan with the water simmer for 25 -30 mins. Squash out juice throw away the peel. Add the 1 KG Strawberry’s and boil slowly for 15 minutes.
Add the 1KG Sugar and rapid boil for 15 minutes.
Tests for set.
When you the jam as set point put into sterilised jars and seal.