Preheat oven to 350F.
Heat oil in a non stick fry pan over medium high heat. Sauté garlic, onion & celery for 2 minutes, then add bacon.
Cook for a further 2 minutes (don't make bacon golden) then transfer to bowl and allow to cool for 10 minutes.
Add remaining filling ingredients into the bowl. Use your hands to mix well.
Lay out a rectangle of pastry, long edge closest to you. Brush egg along one long edge.
Get 1/6th of the filling and shape into a long log shape down the middle of the pastry. Ensure the meat is tight and compact, without gaps.
Brush edge of pastry with egg. Then roll up, finishing with the seam side down.
Roll up, sealing the edge with egg wash.
If you have time/patience, refrigerate for 1 hour (makes it easier/neater to cut)
Cut each log into four equal lengths, or just two if you want full size sausage rolls. Brush the top and sides with egg wash.
Place on baking trays lined with baking paper (or sprayed with oil). Bake for 30 - 35 minutes in total, swapping tray shelves at 20 minutes, or until the pastry is deep golden brown.
Cool slightly on trays. Serve hot or warm with tomato sauce or ketchup!