Look up a hundred biscuit recipes and you'll find some that contain ... they just won't be as tall as the ones pictured here.
While you might have followed your recipe to the letter ... they rise straight and tall. This is what gives the biscuits a seemingly lighter texture and a uniform appearance thanks to the upright ...
The biscuit dough is crumbly so it helps to make the template out of card. The template should be about 9cm/3½in tall and 5cm/2in wide, and roughly the shape of a lightbulb.