The lock dates after 1801/2 which is when William K went into business under his own name. Until then he'd been a partner in Ketland & Co. He died in 1803 but the business continued under his partner, William Allport. Most likely the lock dates from about 1805 or later. The tulips mean absolutely nothing. The lock was made in the B'ham trade by one of the many lock makers. It was sold by the WK firm...
It's the cheapest of export grade locks, without even an internal bridle. It probably didn't have an external bridle as well. Those locks sold for 17s a dozen.