No lock is unbeatable, so the most secure locks are those tested to a recognised standard and fitted to a sound door. For euro cylinders that means TS007 3 star or Sold Secure Diamond (SS312). For wooden doors, look for BS 3621 stamped on the lock's faceplate.
Security comes from the whole door, not one part. Secured by Design notes that a lock's effectiveness also depends on the door, frame and other hardware, which may fail before the lock. For a new door, it lists PAS 24, which tests complete doorsets: the frame, door, hardware and any side panel together. The test is designed to mimic an opportunist burglar using tools that are easy to hide.
Most uPVC and composite doors use a euro cylinder. West Yorkshire Police advise 3 stars as the minimum when upgrading, and a 3 star cylinder with a 2 star security handle makes what they call a 5 star solution. They also say Sold Secure Diamond (SS312) is recognised alongside TS007 at a national level, and Sold Secure says Diamond is equivalent to TS007 3 star.
Wooden front doors usually have a mortice deadlock, a rim lock or both. Secured by Design calls BS 3621 the minimum standard for locks on external or entrance doors. It also lists BS 8621, for locks with a thumb turn inside, and BS 10621, which must only be used where there is another way out. Look for the Kitemark and the standard number on the faceplate.
Insurers can set their own rules. The Master Locksmiths Association says some insurers insist on BS 3621 locks and others do not, so check your own policy. Our BS3621 5 lever mortice lock is £70 for the part, named and priced before anyone sets off. Treat any lock sold as unpickable or unbreakable with caution.
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