Quick note to say we have safely arrived in India and things went just about as planned. A lovely flight with mountain views!
After being hustled at the airport by about 20 men trying to tell us we couldn't cross the border there, we finally got someone to drive us. He waved us in a general direction and we walked along with crowds of Indian and Nepali border-crossers until we were finally waved into an immigration office and told that we were in India. They only had forms for Indian nationals but despite trying to explain that maybe we needed one for foreigners they insisted that it was ok and finally we were allowed through! Very weird experience, but a big relief.
The official was really helpful and explained which trains to take and luckily we were soon on one - 2nd class with wooden seats - and then changed to another, to discover it was 6hrs, but at least these seats were slightly padded!
Arrived 1am and discovered the wonders of 'retiring rooms' in Indian train stations, it was enormous and cost about 1.50!
Then a jeep ride and the toy train to Darjeeling - now enjoying very cold weather and nice tea!