Lord Aristo is an art collector. His favourite painting, Bacon's 'Pope Pious', is stolen. Lord Aristo places an advertisement in the Times newspaper offering a reward of 100,000 to anyone who is able to locate the painting. Advise Lord Aristo in each of the following alternative circumstances:

(a) Canon, a private investigator, is employed by Lord Aristo's insurance company to recover the picture. Canon locates the picture and claims the reward.

(b) Devi sees the advertisement, locates the picture and claims the reward. Devi does not see an advertisement placed in the Independent newspaper withdrawing the offer of a reward before he finds the picture.

(c) Vera, a police detective working on the theft, locates the picture and claims the reward.

(d) Baron Bluster, a friend of Lord Aristo, begins an extensive search for the painting. He telephones Lord Aristo to tell him that he will be meeting an informer that evening who will tell him where the painting is. Lord Aristo tells Baron Bluster not to bother because he has changed his mind about the reward. Baron Bluster goes ahead with the meeting, gets the information and claim the reward