Firstly, Gary, which model Europa do you have?
I have a Type 54 and it has a reinforcing plate spot welded to the inside.
My reinforcing plate is a slightly different shape to the one in Brian's pic.
I can take a pic if you need.
EDIT:
Brian, the red arrow in your pic shows the reinforcing plate on the outside but the insert pic shows it installed on the inside.
Also, the fact that the reinforcing plate is shown as a separate item seems to suggest it was possible to add it at a later date. As I say, mine is spot-welded in position.