I managed to imitate my sister today and lock myself out of the house!
I grabbed my keys and pulled the door shut... then realised that the one key that I needed to unlock all of the doors was still inside the house! I had taken it off my keyring this morning to take with me to the gym (rather than lugging the 7 keys plus torch that I usually carry), and hadn't managed to put it back on my keyring.
Thank you to my father who kindly drove over to let me back in!!