In a heavy-based pan, allow the sugar and syrup to dissolve slowly over a low heat, stirring well. Increase the heat to medium and bring to the boil, stirring constantly. Once you see bubbles, reduce the heat slightly and simmer for five minutes, stirring frequently, until it is a deep golden-brown colour, but ensure that it does not burn.Remove from the heat and stir in the bicarbonate until it froths up, then pour into a well-buttered 10 x 7 inch shallow tin. Leave to cool completely. Break the contents into small pieces. I find it easiest to do this by placing it all in a plastic bag and bashing with a rolling pin. Soften the ice cream very slightly by placing it on "Defrost" in the microwave for one minute. Tip into a bowl and quickly mix in the hokey-pokey. Refreeze until needed.
