Put the syrup, sugar and butter into a pan and boil until the mix goes a light brown colour, stirring continuously. Remove from the heat and stir in the flour, avoiding lumps. Return to the stove and cook, stirring continuously, for 2 minutes (it will colour a little in this time). Remove from the heat and leave to cool for 10 minutes.
Preheat the oven to 200°C/400°F/Gas 6. Take a teaspoonful of the brandy snap mixture in your hand and flatten it out as thin as you can, then place on a baking tray covered with non-stick baking parchment. The snaps spread quite a lot, so start with just four per tray. Place in the oven and cook for 5-8 minutes. They are ready when dark golden and quite bubbly. Remove the tray from the oven and allow to cool a bit. When they are manageable remove from the parchment and fold into cone shapes, resting them in coffee cups until they set. When cold, store in an airtight container in a cool place.