How to make strawberry jam

We had lots of strawberries this year and froze them in the summer when we picked them. We now urgently need the freezer pace so the strawberries have been thawed and made into jam. The recipe used was the basic and traditional one: strawberries simmered; juice of two lemons per kilo of strawberries added; when pulped, add one kilo of sugar for each kilo of fruit; bring back to the boil; keep on a rolling boil until the setting point is reached (ie a spoonful of jam sets on a saucer); then add to hot sterilised jars.