The Norwegian keeper was set for a place on the bench until Richard Wright suffered a knee problem in the warm-up.
It was his first Premiership action for over four years having moved from Spurs to Watford in August 2000. His last was in a 2-1 defeat at West Ham back in November 1998.
"I had a great reception at the start of the second half and I appreciated that because I enjoyed my time here," said Espen, who started 27 games for us between 1996-2000.
"I've great memories of the club and it was great to be remembered by the fans.
"I wasn't expecting to play but there you go, these things can happen in football.
"I was pleased to be playing and would have liked to have won, but that's the way it goes.
"Robbie Keane had a great day but I was just delighted to be playing, it's been a long time since I've played any first team matches so it was nice to be out there. At least I've had a chance to show what I can do."
Espen Baardsen admitted he was touched by his reception at the Lane after being thrown in at the deep end on Sunday.