London: Home of arguably the greatest science fiction television show of all-time, Doctor Who, not to mention $100 taxi rides to or from the airport. I know, I know. . . take the train to Paddington instead. But serious collectors have the ducats for first-class transportation and they were in a buying mood at last week’s contemporary art auctions in London, which coincided with the Frieze Art Fair and are often a harbinger for the spring auction action in New York in May.