>> having initially thought of diana as his girlfriend's little sister, he looked at her with new eyes. and that was the beginning of their relationship. >> she was young. she was beautiful. she was aristocratic, titled. she ticked a lot of boxes for a future king. >> they were chaperoned where they went to the races. they did the routine things in his royal life in a very stayed and proper way. >> charles is pretty old-school. in the royal family you go along with protocol. >> charles used to ring me up and say would you like to come for a walk, would you like to come for barbecues and i would say, yes, please. i thought this was all wonderful. >> january 1981 diana is invited