1
Yarrow Frederick John: Door reinforcing apparatus. Yarrow Frederick John, April 25, 1990: GB2224065-A (3 worldwide citation)

Door reinforcing apparatus (2) comprising a lock guard (4) for fitting to an outer face (10) of a door (12) adjacent a lock (14) in the door (12), and fixing means (18) for fixing the lock guard (4) in position; the lock guard (4) being larger than the lock (14) and having a side wall (20) with key ...


2
Yarrow Frederick John: Security fasteners for preventing theft or vandalism. Yarrow Frederick John, December 5, 1990: GB2232218-A (3 worldwide citation)

A bolt or screw (2) has an external screw thread (4) for screwing into an object, a first internal thread (6) of the same hand as the external thread (4) and engageable by an externally screw-threaded tool (not shown) for driving the bolt or screw (2), and a second internal thread (8) of opposite ha ...


3
Yarrow Frederick John: Apparatus for restricting key access to a lock.. Yarrow Frederick John, January 20, 1993: GB2257743-A (1 worldwide citation)

Apparatus (2) restricting key access to a key-operated lock, which apparatus (2) comprises a plate member (4) for fitting to a door about a keyhole for the lock, an aperture (6) in the plate member (4) for permitting access to the keyhole by a key, a cover member (8) for covering the keyhole, a rece ...