Preheat oven to Gas Mark 3, 160ºC, 325ºF.
Throw the slice of bread, garlic, seasoning and herbs into a food processor. Whizz together until the bread is mixed to a fine crumb. Place in a large bowl and add the mince.
Line the bottom of a 1 litre or 2 pint terrine or loaf tin with 3-4 rashers of streaky bacon laid lengthways. Add the fragrant thyme sprigs and fill the terrine with half of the raw meat mixture.
Now carefully lay the hard boiled eggs on top of the meat, place the leeks lengthways over the eggs. Cover with the remaining mixture and lightly press so that it fills every corner, then cover with another 3-4 more rashers.
Half fill a roasting tin with boiling water and place the filled terrine tin in the centre, then cover with foil. Place in a preheated oven and cook for about 1 hour until the mixture is set and cooked through, then serve in thick slices.