Direct flight time London to kolkata?

A random search for flights London Heathrow (LHR) to Kolkata (CCU) shows: OPTION 1: 13hr 30min with a stop at Delhi (DEL) (no change of aircraft)

LHR - CCU Air India Flt 112 Dep 09:30pm 25Jun,Thu

Flight Duration: 13hr 30min;

1-way Economy fare US$210.oo + Taxes & Fees US$198.oo There appears to be no nonstop flights between the two cities.