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 (because you don't want to mix it together with your hands while its hot).
Add remaining Filling ingredients into the bowl. Use your hands to mix well.
Using a plate, divide all filling into 3 parts, then halve those each again (making 6 equal parts).
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 on the edge with egg wash on it.
If you have time/patience, refrigerate for 1 hour (makes it easier/neater to cut).