Mix the sausagemeat, celery, onion and herbs in a large bowl.
Roll out the pastry onto a floured surface into a long rectangle. Cut into 6 strips (roughly 3 x 12").
Spoon a thin strip of the filling along the middle of each strip.
Brush the egg on one side of the strip, then fold the pastry over to seal. Prick with a fork, brush with the top with egg, then cut each rolled strip into 3 or 4 rolls.
Bake at 220 degrees C for 15 minutes, then reduce the heat to 180 degrees C to bake for another 15 minutes.