Your favourites list is session based, which means that when you exit London Picture Archive by closing your browser tab or window, your favourites list will be deleted. If you want to compile lists of London Picture Archive images over a longer period of time or plan to leave your browser open for several hours, we suggest using the option to ‘Create a PDF of Results’ on the Favourites page at regular intervals to ensure that you have a copy of your list."> Favourites - London Picture Archive