1. Grease the tin , put nuts and place it in the oven to make them just warm
2. Put the sugars, corn syrup and water in a large heavy based sauce pan and heat gently stirring all the time until the sugar has dissolved.
3. Add the butter to the mixture, stir until it has melted, then bring it to boil very gently without stirring until it reaches hard crack stage
4. Quickly stir in the bi carbonate of soda and slightly warmed nuts.
5. Pour the mixture into greased tin immediately and leave it to cool.
6. Mark into bars with sharp knife when almost set and break into pieces when completely cold.