Is it illegal for my former Landlord to open my mail? I moved out of the flat last month and he has opened two letters addressed to me at the property he rented to me.
It is not illegal for anyone to open your mail. It is certainly discourteous, but not illegal. You should have arranged for all your mail to be forwarded to your new address through the Royal Mail Redirection Service so that the only mail that would continue to be delivered to the property is junk mail.
Any subsequent mail received at the property could either be binned, opened, or destroyed by either the new occupant, or the Landlord and you would be none the wiser. One always relies on the integrity of either new occupiers or former Landlords to forward unopened mail, but of course there is no obligation on anyone to do so and certainly not for any indefinite period.