Always buy a type of lock which is approved by insurance companies. They are more likely to accept an insurance risk on a house fitted with these locks and, in the event of a break-in, view a claim more favourably. Don’t assume that burglars only break into houses that are filled with valuables; virtually every house possesses something of value such as a television or computer.
Although your choice of mortise lock will be determined by how much security you want, a general guide is to fit deadlocks on external doors and latched mortise locks on internal doors. Even a mortise lock can be picked or sprung by an expert, but the chances of this happening are remote if you choose a lock with a complex mechanism. This is largely determined by how many levers and/or tumblers the lock is fitted with, and this number is usually stamped on the faceplate.