The U’s headed to Kenilworth Road off the back of their goalless draw at home to Burnley, relegated from the Premier League last season, to face another side playing in the top flight just a few months ago, in the form of the Hatters.
Jordan Clark gave the home side a 10th minute lead, and that was doubled by Tom Krauss eight minutes before the break.
Tyler Goodrham’s lovely first-time volley brought United back to within a goal shortly before half-time, and nine minutes into the second half, Ruben Rodrigues levelled the match with a neat finish.
The Hatters would ultimately play the closing stages with 10 men after substitute Liam Walsh was shown a straight red card for a lunge on Siriki Dembele, capping a breathless affair which had a little bit of everything.
U’s head coach Buckingham said: “That was a wonderful advert for our football club. We’ve come again to another Premier League team three days after playing another one.
“We gave away two sloppy goals which put them two up. I just said to them in there, we spoke about the effort and the work rate from Saturday’s game, and to add quality with the ball.
“I’m delighted with what I’ve just seen. To come back into the game after two setbacks and create several chances.
“In the second half, I thought we played some wonderful football and should’ve gone on to win the game.
“I’m delighted with the way that we’ve played and I’m delighted with coming away from the last two games with some points, and it puts us in a good position to go again on Saturday.”
Buckingham also recognised the importance of Goodrham’s goal just before half-time, as it helped swing momentum the way of the U’s going into the second half.
Buckingham said: “We had two big moments before that. We had a cross that Tyler put in for Owen Dale, and it got cleared centrally in the six-yard box, and Owen couldn’t quite get there.
“There was a cutback for Idris El Mizouni which he put the other side of the post, so there were two good chances there, and it was important we got the next goal.
“To do that just before half-time gave us a bit of a springboard. We made some changes at half-time, not just in personnel, but with a couple of things we wanted to probe a little bit more. I’m just delighted with the performance.”