That was given after David Mirfin had brought down Luke Moore - an incident that led to McCann's dismissal as he showed his disgust to the referee.
An incident packed game also saw a Moore header ruled out for offside, but Baggies boss Roberto di Matteo will be happy enough with three points that keeps his side in the automatic promotion places above Nottingham Forest.
He will also be aware things could have been different had Scunthorpe not shot themselves in the foot with two needless sendings off.
The first, in particular, came at a time when the home team were resurgent, and it was not until Zuiverloon slid home from Chris Brunt's pass that West Brom looked confident of securing a win they just about deserved.
Scunthorpe manager Nigel Adkins: "I know the referee does not have access to technology when he is making his decisions.
"But I have looked at both penalties on the DVD, the first was a good challenge and with the second both players made contact with the ball at the same time.
"We also had a player sent off on Boxing Day at Middlesbrough and these decisions are very disappointing.
"I will be going in to see the referee because he has sent one of my players off for using foul and abusive language.
"But I will be wanting to talk to him about the manner in which he has spoken to some of my players during the game."
West Brom manager manager Roberto di Matteo: That's six points out of six from the two Christmas games and just what we wanted to keep up the pressure at the top of the table.
"I thought we were in control for most of this game. We might have been more than one goal in front by the interval and it was disappointing to see Scunthorpe come back on level terms from a set-piece situation.
"As far as the two penalties are concerned, I did not really get a good view of the first decision but the second looked a clear penalty to me.
"My players had to be careful to keep their discipline because the home crowd were trying to influence the decisions of the referee."
90:00+3:11 The referee blows for the end of the match.
90:00+2:47 Ben May concedes a free kick for a foul on Shelton Martis. Free kick taken by Dean Kiely.
90:00+2:32 Free kick awarded for a foul by Luke Moore on Sam Togwell. David Mirfin takes the direct free kick.
90:00+0:08 Luke Moore concedes a free kick for a foul on Sam Togwell. Joe Murphy takes the direct free kick.
89:34 Sam Togwell gives away a free kick for an unfair challenge on Jerome Thomas. Luke Moore takes the direct free kick.
87:09 Substitution Shelton Martis replaces Chris Brunt.
86:34 Substitution Ben May on for Martyn Woolford.
85:10 Chris Brunt provided the assist for the goal.
85:10 GOAL - Gianni Zuiverloon:Scunthorpe 1 - 3 West Brom Gianni Zuiverloon gets on the score sheet with a goal from inside the penalty area to the top right corner of the goal. Scunthorpe 1-3 West Brom.
84:20 Luke Moore has an effort at goal from 18 yards. Save by Joe Murphy. The referee blows for offside. Free kick taken by Joe Murphy.
83:37 Effort from outside the penalty box by Chris Brunt goes wide right of the target.
83:12 The ball is crossed by Jerome Thomas.
82:38 Gianni Zuiverloon produces a drilled right-footed shot from 20 yards. Save by Joe Murphy. Corner taken by Jerome Thomas played to the near post, Marcus Williams manages to make a clearance.
81:39 Substitution Jonathan Forte is brought on as a substitute for Garry Thompson.
81:39 Chris Brunt takes a shot from just inside the penalty box which clears the crossbar.
78:26 Shot by Luke Moore from 18 yards. Blocked by Rob Jones. Corner taken by Chris Brunt from the right by-line to the near post, clearance made by Paul Hayes.
78:15 Centre by Gianni Zuiverloon, clearance by David Mirfin.
76:42 Substitution (West Brom) makes a substitution, with Youssouf Mulumbu coming on for Graham Dorrans.
76:42 Centre by Graham Dorrans, clearance made by Marcus Williams.
75:18 Booking Gonzalo Jara booked.
73:59 Michael O'Connor fouled by Gonzalo Jara, the ref awards a free kick. Direct free kick taken by Joe Murphy.
73:59 Power penalty taken by Graham Dorrans saved by Joe Murphy. Scunthorpe 1-2 West Brom.
73:59 Sent off Grant McCann is sent off by the referee.
73:25 Luke Moore fouled by David Mirfin, the ref awards a Penalty.
70:58 Gianni Zuiverloon sends in a cross. Chris Wood is flagged offside by the assistant referee. Free kick taken by Joe Murphy.
69:12 Foul by Gianni Zuiverloon on Martyn Woolford, free kick awarded. Direct free kick taken by Joe Murphy.
67:39 Grant McCann sends in a cross, Martyn Woolford takes a shot. Save by Dean Kiely.
65:12 GOAL - Graham Dorrans:Scunthorpe 1 - 2 West Brom Placed penalty scored by Graham Dorrans. Scunthorpe 1-2 West Brom.
64:05 Booking Joe Murphy goes into the referee's book for dissent.
63:57 Penalty awarded for a foul by Rob Jones on Graham Dorrans.
62:54 Graham Dorrans takes a long range shot harmlessly clearing the crossbar.
62:30 Free kick awarded for a foul by Garry Thompson on Abdoulaye Meite. Direct free kick taken by Gonzalo Jara.
Correction - 60:45 Substitution Chris Wood joins the action as a substitute, replacing Simon Cox.
Correction - 60:45 The ball is crossed by Graham Dorrans, Luke Moore takes a shot.
60:45 Substitution Chris Wood comes on in place of Luke Moore.
60:45 Centre by Graham Dorrans, Luke Moore takes a shot.
60:45 Sent off Andrew Wright shown a red card.
Correction - 60:03 Foul by Andrew Wright on Jerome Thomas, free kick awarded.
60:03 Free kick awarded for a foul by Andrew Wright on Jerome Thomas.
59:13 Centre by Gianni Zuiverloon, save by Joe Murphy.
57:40 Jerome Thomas produces a right-footed shot from just outside the area that goes harmlessly over the bar.
57:06 A cross is delivered by Graham Dorrans, Luke Moore takes a shot. Save made by Joe Murphy.
56:46 Sam Togwell delivers the ball, save made by Dean Kiely.
56:04 Andrew Wright fouled by Jerome Thomas, the ref awards a free kick. Joe Murphy takes the free kick.
55:12 Shot by Garry Thompson. Dean Kiely makes a save.
54:44 Chris Brunt produces a cross, Joe Murphy makes a save.
53:31 Substitution Martyn Woolford joins the action as a substitute, replacing Josh Wright.
53:31 Graham Dorrans has an effort at goal from long range that misses to the right of the target.
52:20 Free kick awarded for a foul by Abdoulaye Meite on Garry Thompson. Grant McCann sends in a cross, Sam Togwell takes a shot. Save by Dean Kiely.
51:50 Gianni Zuiverloon crosses the ball.
50:53 The ball is crossed by Paul Hayes, Jonas Olsson manages to make a clearance.
49:34 Short corner taken by Paul Hayes from the right by-line, Effort on goal by Michael O'Connor from deep inside the penalty area misses to the right of the target.
48:52 The free kick is swung in left-footed by Grant McCann, clearance by Abdoulaye Meite.
48:52 Booking Jerome Thomas goes into the book.
48:35 Handball decision goes against Jerome Thomas. Grant McCann takes the direct free kick. Andrew Wright fouled by Jerome Thomas, the ref awards a free kick.
47:54 Chris Brunt produces a cross.
47:23 A cross is delivered by Marek Cech, clearance by Rob Jones. Outswinging corner taken left-footed by Chris Brunt played to the near post, clearance by Andrew Wright.
46:04 GOAL - Rob Jones:Scunthorpe 1 - 1 West Brom Goal scored by Rob Jones from close in low into the middle of the goal. Scunthorpe 1-1 West Brom.
45:21 Corner taken by Grant McCann from the right by-line. Shot from 20 yards from Michael O'Connor. Save made by Dean Kiely.
45:01 The referee blows his whistle to start the second half.
Half Time
45:00+1:04 The half-time whistle blows.
43:24 Sam Togwell delivers the ball, clearance made by Abdoulaye Meite.
41:41 Centre by Garry Thompson, clearance made by Jonas Olsson. Corner taken by Grant McCann played to the near post, free kick awarded for a foul by Rob Jones on Jonas Olsson. Dean Kiely restarts play with the free kick.
39:39 Michael O'Connor challenges Jerome Thomas unfairly and gives away a free kick. Chris Brunt produces a shot on goal direct from the free kick.
38:11 Garry Thompson is ruled offside. Dean Kiely restarts play with the free kick.
37:34 Shot from long distance by Chris Brunt misses to the right of the target.
36:30 Direct free kick taken by Marek Cech.
36:30 Booking Andrew Wright goes into the referee's book for unsporting behaviour.
36:19 Foul by Andrew Wright on Jerome Thomas, free kick awarded.
35:53 Unfair challenge on Garry Thompson by Marek Cech results in a free kick. Andrew Wright takes the free kick.
32:47 Paul Hayes sends in a cross, Jonas Olsson makes a clearance.
32:23 Centre by Graham Dorrans, clearance made by Andrew Wright.
31:31 Graham Dorrans takes a inswinging corner from the left by-line to the near post, clearance made by Grant McCann.
28:50 Abdoulaye Meite gives away a free kick for an unfair challenge on Paul Hayes. Direct free kick taken by Michael O'Connor. Paul Hayes is flagged offside by the assistant referee. Dean Kiely takes the free kick.
28:15 The official flags Simon Cox offside. Indirect free kick taken by Joe Murphy.
26:22 Jonas Olsson sends in a cross, save made by Joe Murphy.
23:01 Marcus Williams produces a cross, Michael O'Connor produces a right-footed shot from the edge of the box and misses to the right of the target.
21:56 Chris Brunt takes a shot from 35+ yards.
21:38 Centre by Michael O'Connor, Abdoulaye Meite manages to make a clearance.
20:05 Luke Moore takes a shot. David Mirfin gets a block in. Graham Dorrans takes a inswinging corner from the left by-line played to the near post, Abdoulaye Meite takes a shot. Comfortable save by Joe Murphy.
18:56 GOAL - Graham Dorrans:Scunthorpe 0 - 1 West Brom Graham Dorrans grabs a goal from inside the penalty area low into the middle of the goal. Scunthorpe 0-1 West Brom.
18:37 The ball is delivered by Marek Cech, save by Joe Murphy.
17:52 Jerome Thomas crosses the ball, save made by Joe Murphy. Graham Dorrans crosses the ball, Rob Jones manages to make a clearance.
16:31 Andrew Wright delivers the ball, Header from deep inside the area by Garry Thompson goes harmlessly over the crossbar.
16:13 Grant McCann takes a shot. Blocked by Gonzalo Jara.
15:49 Andrew Wright fouled by Simon Cox, the ref awards a free kick. Grant McCann takes the direct free kick.
14:54 Handball decision goes against Luke Moore. Free kick taken by Joe Murphy.
13:08 Free kick awarded for an unfair challenge on Marek Cech by Garry Thompson. Dean Kiely takes the direct free kick.
10:54 The ball is delivered by Graham Dorrans, Simon Cox has a headed effort at goal from just inside the area that misses to the right of the goal.
8:49 A cross is delivered by Jerome Thomas, save by Joe Murphy. Effort on goal by Chris Brunt from deep inside the penalty area misses to the right of the goal.
8:06 A cross is delivered by Garry Thompson, save by Dean Kiely.
6:54 Effort from deep inside the area by Garry Thompson misses to the left of the target.
6:13 Sam Togwell produces a cross.
4:33 Jerome Thomas has an effort at goal. Joe Murphy makes a fantastic save.
3:54 Corner taken right-footed by Graham Dorrans, clearance made by Paul Hayes.
2:17 Garry Thompson delivers the ball.
0:43 Jerome Thomas takes a shot. Save made by Joe Murphy. Foul by Sam Togwell on Jerome Thomas, free kick awarded. Free kick crossed left-footed by Chris Brunt, David Mirfin manages to make a clearance.
0:00 The match gets underway.
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