Using concepts of Intention, Consideration, Formalities, Capacity and Illegality

Question 3 : Read the following scenario and provide explanations to express your opinions using your own words

SCENARIO: Judy runs an antique jewellery store. One evening a hooded man stormed into her store and robbed $100,000 from the register. One month later, Judy decides to run a stocktake sale from 5pm to midnight, but is still afraid of being robbed. She asks a police officer she knows, Peter, if he will attend her store while the stocktake sale is on and provide her with personal protection from any potential robbers. She offers to pay him $1000 for his effort. Peter agrees, even though it is normally his night off duty. During the duration of the sale, Peter stays by Judy's side and protects her. The next day, Peter attends the store to collect his payment and Judy refuses to pay him for "doing his duty". Can Peter sue Judy to enforce their verbal agreement?