The pressure was building on Lomas following six Championship games without a win since he replaced long-serving manager Kenny Jackett.
But the Lions finally found their roar thanks to goals from Liam Trotter, Nicky Bailey and Steve Morison.
"It was an important result, for the club and the manager," said defender Robinson.
"He's worked very hard since he has been here. I'm sure he will savour his first three points, because they have been a little while coming.
"There have been a lot of changes at the club recently. When you have the same manager for six years, it does take a little while and there's a period of transition.
"Hopefully we can build on this result."