Pre-heat oven to 160 degrees Celsius.
Cover the sultanas with water and bring to the boil (and yes, they were soaked overnight).
Boil for 15 minutes and drain.
Add butter to hot sultanas.
Beat eggs and sugar together.
Add to sultana mixture.
Then add the sifted flour and baking powder.
Add the lemon essence and mix well.
Bake in a 20cm tin for about 1.5 hours.
Test to see if it's done, if not return to oven for a few minutes and check again.
Let cake cool in tin 10 minutes before turning out to cool on a cake rack.