Looting London

London has been looted! Five of its rarest treasures have been stolen on the same night: one of the Crown Jewels from the Tower of London, gold reserves from the Bank of England, top secret files from Big Ben, a priceless Incan artifact from the British Museum, and a Van Gogh from the National Gallery. You are a famous London sleuth; can you interview the four witnesses, gather their clues, apprehend the thieves and recover the loot?