His approach bears out some of the studies of robbery in the 1970s-1980s, that suggested that shifting from gun to knife and club robbery (mostly caused by mandatory sentencing for gun robberies) had unexpected effects, including:

Gun robbers were more likely to hit stores, where the money is, while knife and club robbers hit individuals -- less profit, but more easily done with a hand weapon.

Gun robbers who did target individuals went for males in their prime -- likely to have more money -- while knife and club robbers went for women and the elderly -- easier to intimidate or beat.

Some robbers did give up robbery, but the remainder (faced with much less money per crime) increased their frequency of robbery enough to make up for it.

Gun robbers usually relied on intimidation. When they gave up guns, robbers tended to favor clubs rather than knives, and to actually beat the victim rather than threaten.

In this case of the British killer, you notice immediately that his targets were in their 60s and 70s, and two of four victims were women.