Preheat oven to 350°F (180°C). Line a baking sheet with parchment paper.
Soak breadcrumbs in milk. In a large pan over medium heat, add butter and cook onion, garlic, celery and carrot until soft, about 10 minutes. Remove from heat and stir in Worcestershire, 1/4 cup (60 mL) ketchup, dry mustard, thyme. Transfer to a large bowl.
Add pork, beef, veal, soaked breadcrumbs, eggs and parsley. Season with salt and pepper. Using hands, mix until just combined; do not overmix.
Transfer meatloaf mix to baking sheet and form into a long mummy shape. Brush remaining ketchup over entire shape. Drape bacon slices over to form wrapping.
Bake meatloaf for about 50 minutes to an hour, or until juices run clear and internal temperature reaches 160°F (70°C).