British Airways operate an all Club World Business Class service on their sole A318 between London City and New York JFK. This is possibly the World's Smallest Commercial plane flying Trans-Atlantic. BA1 flight has the BEST service on any British Airways flight, most passengers are high net worth individual and treated like flying private jet.
The outbound route from London City requires a tech stop at Shannon, where passengers are pre-cleared for US immigration and customs, before arriving at New York JFK. Perhaps saving the best till last, it took me just 5 minutes from walking outside the plane to the street at New York JFK!