Heat the oven to 220ºc / 200ºc fan / 430ºf and place a lined baking tray in the oven to preheat.
In a large bowl, rub the butter into the flour, salt, baking powder and sugar mixture until breadcrumbs are formed.
Alternatively, tip the flour, salt, baking powder, sugar and butter into a food processor and pulse until it resembles bread crumbs
Add the lemon juice to the dry mixture with the vanilla
Slowly add the warm milk. Mix in while you add in the liquid as you may not need all of it (I often only use 100ml or so)
Dust the work surface with some flour and tip the dough onto it - fold the dough over a few times so it is smooth but do not over work it!
Roll the dough out until it is about 4-5cm thick.
Dip a 5cm round cutter into the spare flour and cut out the scones - you will probably get four out of the first go. Repeat this again till you finish up all the dough.
Take the tray out of the oven carefully and place the scones onto it - brush the tops with the beaten egg so its glazed and bake in the oven for 10 minutes - leave to cool slightly when baked.
Serve with clotted cream and jam for the stereotypical deliciously yummy scone!
Notes
I often find these are delicious when still warm as it makes them lighter and fluffier - however they do last in an airtight container for 2-3 days