Danny Hylton grabbed his first goal since October as he headed in from close range just before the hour mark, before James Collins fired in his 20th of the campaign after some brilliant work from Kazenga LuaLua in the first minute of second half added time.
The result means the Hatters maintain their spot at the top of the league – five points clear of second placed Barnsley and seven ahead of Sunderland in third spot, who have a game in hand.
Harford said: "It was very, very tough in all fairness. We knew what they were all about, the manager can be different and he played a different shape and he made it difficult for us to have a go.
"They pressed us really, really high, put us under pressure. They played quite a high line and in the first half, maybe if we had a bit more quality we could have got in behind and allowed more spaces behind, but the space was so condensed today that it was difficult to get any fluency in our game. But, overall, we are absolutely thrilled with the performance and the result.
"Barnsley would have still been behind us in the table whatever their result earlier, so that gives you a bit of security. I keep saying it, but we have to look after ourselves. We have to look after our game and I thought we did that excellently today. We can't affect what other teams are doing, we will just keep trying to churn out results and win every game. We approach every game with a winning mentality and hopefully we can carry that on."