Trimble sang 'Caliban's Dream', a song written by Underworld's Rick Smith, which accompanied the Olympic Flame as it entered the stadium last night (July 27).
The singer was personally chosen by ceremony director Danny Boyle for the key role in the show.
Recalling the events that led to his appointment, Trimble said: "I remember getting a call from my manager one morning while I was on tour in America. It woke me up and I was half asleep and hungover - he told me that Danny wanted me to come and perform a song at the Olympics.
"I listened and then went back to sleep. When I woke up again I actually thought the call had been a dream. My manager called back and after a lot of convincing that it was, in fact, a real genuine offer, I obviously said yes."
On the event itself, Trimble said: "I'm really proud of the performance. I have so much respect for the team that put it all together. Danny always made time to sit with me one on one and go through things and see how everything was going and with Rick we worked one on one too.
"In the studio, on the phone, it just felt so personal. Not like something that's gone out worldwide! I'm sure it'll take a few months for the reality to fully sink in."
Listen to Alex Trimble sing 'Caliban's Dream' below:
Photo gallery - London 2012 Olympics Opening Ceremony:
Copyright: PA Images Anthony Devlin/PA Wire