The failed robbery took place on Saturday night. The thief is seen sauntering into the store smoking a cigarette, which Mr Alexander promptly asks the man to put out.
The thief then quickly reaches for his gun while demanding all the money in the til.
But the clerk's training and instinct took over, and he grabbed his own Walther PPX 9 mm handgun from his back pocket while blocking the thief's aim with his other hand.