Crystal Palace hadn’t lost at home since the opening day of the season, but the automatic promotion hopefuls were no match for a rampant Blues side.
Having put an end to the Londoners' impressive home record, Birmingham extended their winning run to three games, scoring eight goals in the process.
And Clark was quick to point out how pleased he was with the result in the capital.
The Blues boss told bcfc.com: “I think when you come to a place like this; you expect it to be a close and tough game, which it was, but in my wildest dreams I didn’t expect the margin of victory to be that big.
“But in all honesty it was fully deserved as well; it wasn’t a fluke.”
Clark’s men have lost just twice in their last 13 league encounters, a sequence of form that has catapulted them up to 10th in the npower Championship.
He continued: “We’ve been a completely different team since just before Christmas. We were on a rocky road in the early part of the season but we’ve turned it around and I think its credit to the players. They’ve done what I’ve been asking. I just get frustrated when we play like that today – to think if we started doing it a bit earlier then we might have been nearer the top of the division.
“Because the team that finished sixth last season, Cardiff (City), finished with 75 points. I’m not sure the team that finishes sixth this season will have as many points.”
Blues now turn their attention to the big derby clash with struggling Wolves on Easter Monday.
Clark added: “Now we have to go and replicate a performance like that at St. Andrew’s for our magnificent supporters and go and beat our local rivals on Monday.”