The Rightful Owner

Wilbur Smith, an insurance agent working in London, gets a call to attend a funeral of a person who he thinks he had met sometime back for some insurance deal. The only apparent relation that he has with the dead man is a common surname. Wilbur attends the ceremony and while coming back, receives a few old coins. On his friend's insistence, he again visits the dead man's estate to know more about the coins. This time he comes across an old diary. The coins, the diary and some instructions from the dead man's sister take him to India. Thus begins the search for the rightful owner of the coins. This search unveils many other mysteries besides unmasking the rightful owner. So who is he? Why were the coins given to Wilbur?