Preheat oven to 190 C /375 F or gas mark 5. Lightly grease a shallow tin measuring approximately 30 cm x 18.5 cm or 13in x 7.5 in.
Melt the butter in a medium saucepan. Weigh out the sugar, then weigh the syrup by spooning it on top of the sugar. Add this to the melted butter and heat through to slightly dissolve the sugar. Remove the pan from the heat and add the oats. Spread the mixture in the tin and pat down to make sure it is even. Bake for 20- 30 minutes until just golden brown. Be careful not to over bake it as it will make the flapjacks too hard and crunchy. As soon as you take them out of the oven score them into bars and leave in the tin to cool. This bit will be the most difficult part of the process!
I am a great tinkerer when it comes to recipes so I would normally be tempted to add a little bit of cinnamon or perhaps some finely chopped and roasted hazelnuts or even some chocolate chips to make this even better. This goes against tradition so I shall leave the tinkering to you this time. I have to admit that the simple and unadulterated version is fab and perhaps adding anything else is just gilding the lilly.