We picked this British Standard 5 lever lock to open a commercial premises for the client. The main key had been lost and the spare key was several hours away.
BS locks are designed to be difficult to open without the key. They have to have a certain number of possible keys, a minimum specific time for a cutting attack on the bolt, and various other limits. They certainly aren’t easy to pick unless you know what you’re doing. This lock is a Union Strongbolt and is one of the more common locks.