Add the vegetable oil to a pan, and warm over a medium heat. Once the oil is hot (but not smoking), add the popcorn kernels. Shake to distribute and coat the kernels in oil. Put the lid on the pan, but leave a small crack for steam to escape. Place the lid on fully once the first kernel has popped. When the popcorn starts to pop shake the pan to ensure the kernels are evenly distributed. Once the popping slows take it off the heat.
Pour the popcorn into a bowl to cool, and remove unpopped kernels. Lightly salt to taste.
Mix the sugar and honey in a small saucepan and bring to the boil. Reduce the heat and simmer for 2 minutes, before removing from the heat and adding the peanut butter. Stir thoroughly until the peanut butter has melted, then add the vanilla.
Pour the peanut mixture over the popcorn and stir until all the popcorn is coated. Leave to cool for 10-15 minutes and then serve.