1.Line two baking trays with baking paper. Wash apples under cold water, stand on a cake rack until completely dry (do not rub apples with a cloth). Push a wooden stick three quarters of the way through each apple from stem end.
2.In a large saucepan, combine sugar, water, glucose and colouring. Stir over low heat, until sugar dissolves. Bring to the boil. Boil, uncovered, about 10 minutes or until mixture reaches 154°C on a sugar thermometer.
3.Remove from heat; allow bubbles to subside. Tilt pan slightly to one side; carefully dip an apple in toffee; twist slowly to coat apple completely. Remove apple slowly (air bubbles will form if the apples are dipped too quickly).
4.Twirl apple around a few times over pan then place on prepared tray. Repeat with remaining apples and toffee. Leave toffee apples to set in a cool, dry place. Do not refrigerate.
You will know when your sugar syrup is ready in Step 2 when drops of mixture snap and immediately harden when placed in a glass of iced water. Not suitable to freeze or microwave. Toffee apples can be made up to two days ahead.