Boil cubed potatoes until fork tender (about 8minutes), drain, mash with butter, salt and milk until smooth. Keep warm.
Meatballs
While potatoes are cooking soak the slice of bread in the milk, gently squeeze out excess milk then add to a mixing bowl with the rest of the meatball ingredients. Mix together with your hands (don't overwork it), season generously with salt and pepper and roll into pingpong size balls.
Heat the olive oil in a pan and fry the meatballs for 3 minutes each side until nicely coloured, then remove onto a plate (they don't have to be fully cooked).
In the same pan add a small knob of butter and stir in the flour, once fully incorporated remove from the heat and slowly pour in the beef stock (I used a whisk at this stage), return the pan to the heat and whisking/stirring continuously.
The sauce will start to thicken, now add all the remaining gravy ingredients, once fully incorporated, reintroduce the meatballs to the pan (along with any juice) and gently simmer for a few minutes until piping hot.
Serve on mashed potato with any leftover dill for garnish.